Container Soils - Water Movement & Retention VI

tapla (mid-MI z5b-6a)January 28, 2009

I first posted this thread back in March of 05. Five times it has reached the maximum number of posts to a single thread (150), which is much more attention than I ever imagined it would garner. I have reposted it, in no small part, because it has been a wonderful catalyst in the forging of new friendships and in increasing my list of acquaintances with similar growing interests. The forum and email exchanges that stem so often from the subject are in themselves, enough to make me hope the subject continues to pique interest and hopefully, the exchanges provide helpful information. Most of the motivation for posting this thread again comes from the participantsÂ reinforcement of the idea that some of the information provided in good-spirited collective exchange will make some degree of difference in the level of satisfaction of many readersÂ growing experience.

I'll provide links to the previous five threads at the end of what I have written - in case you have interest in reviewing them. Thank you for taking the time to look into this subject - I hope that any/all who read it take at least something interesting and helpful from it. I know it's long, but I hope you find it worth the read.

Al

Container Soils - Water Movement and Retention - A Discussion About Soilssize>

As container gardeners, our first priority should be to insure the soils we use are adequately aerated for the life of the planting, or in the case of perennial material (trees, shrubs, garden perennials), from repot to repot. Soil aeration/drainage is the most important consideration in any container planting. Soils are the foundation that all container plantings are built on, and aeration is the very cornerstone of that foundation. Since aeration and drainage are inversely linked to soil particle size, it makes good sense to try to find and use soils or primary components with particles larger than peat. Durability and stability of soil components so they contribute to the retention of soil structure for extended periods is also extremely important. Pine and some other types of conifer bark fit the bill nicely, but IÂll talk more about various components later.

What I will write also hits pretty hard against the futility in using a drainage layer of coarse materials as an attempt to improve drainage. It just doesn't work. All it does is reduce the total volume of soil available for root colonization. A wick can be employed to remove water from the saturated layer of soil at the container bottom, but a drainage layer is not effective. A wick can be made to work in reverse of the self-watering pots widely being discussed on this forum now.

Since there are many questions about soils appropriate for use in containers, I'll post basic mix recipes later, in case any would like to try the soil. It will follow the Water Movement information.

Consider this if you will:

Soil fills only a few needs in container culture. Among them are: Anchorage - A place for roots to extend, securing the plant and preventing it from toppling. Nutrient Retention - It must retain enough nutrients in available form to sustain plant systems. Gas Exchange - It must be sufficiently porous to allow air to move through the root system and by-product gasses to escape. Water - It must retain water enough in liquid and/or vapor form to sustain plants between waterings. Most plants can be grown without soil as long as we can provide air, nutrients, and water, (witness hydroponics). Here, I will concentrate primarily on the movement of water in soil(s).

There are two forces that cause water to move through soil - one is gravity, the other capillary action. Gravity needs little explanation, but for this writing I would like to note: Gravitational flow potential (GFP) is greater for water at the top of the container than it is for water at the bottom. I'll return to that later. Capillarity is a function of the natural forces of adhesion and cohesion. Adhesion is water's tendency to stick to solid objects like soil particles and the sides of the pot. Cohesion is the tendency for water to stick to itself. Cohesion is why we often find water in droplet form - because cohesion is at times stronger than adhesion; in other words, waterÂs bond to itself can be stronger than the bond to the object it might be in contact with; in this condition it forms a drop. Capillary action is in evidence when we dip a paper towel in water. The water will soak into the towel and rise several inches above the surface of the water. It will not drain back into the source, and it will stop rising when the GFP equals the capillary attraction of the fibers in the paper.

There will be a naturally occurring "perched water table" (PWT) in containers when soil particulate size is under about .125 (1/8) inch.. This is water that occupies a layer of soil that is always saturated & will not drain from the portion of the pot it occupies. It can evaporate or be used by the plant, but physical forces will not allow it to drain. It is there because the capillary pull of the soil at some point will surpass the GFP; therefore, the water does not drain, it is perched. The smaller the size of the particles in a soil, the greater the height of the PWT. This water can be tightly held in heavy (comprised of small particles) soils and ÂperchÂ (think of a bird on a perch) just above the container bottom where it will not drain; or, it can perch in a layer of heavy soil on top of a coarse drainage layer, where it will not drain.

Imagine that we have five cylinders of varying heights, shapes, and diameters, each with drain holes, and we fill them all with the same soil mix, then saturate the soil. The PWT will be exactly the same height in each container. This saturated area of the container is where roots initially seldom penetrate & where root problems frequently begin due to a lack of aeration. Water and nutrient uptake are also compromised by lack of air in the root zone. Keeping in mind the fact that the PWT height is dependent on soil particle size and has nothing to do with height or shape of the container, we can draw the conclusion that: Tall growing containers will always have a higher percentage of unsaturated soil than squat containers when using the same soil mix. The reason: The level of the PWT will be the same in each container, with the taller container providing more usable, air holding soil above the PWT. From this, we could make a good case that taller containers are easier to grow in.

A given volume of large soil particles has less overall surface area when compared to the same volume of small particles and therefore less overall adhesive attraction to water. So, in soils with large particles, GFP more readily overcomes capillary attraction. They drain better. We all know this, but the reason, often unclear, is that the height of the PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. Mixing large particles with small is often very ineffective because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential. An illustrative question: How much perlite do we need to add to pudding to make it drain well?

We have seen that adding a coarse drainage layer at the container bottom does not improve drainage. It does though, reduce the volume of soil required to fill a container, making the container lighter. When we employ a drainage layer in an attempt to improve drainage, what we are actually doing is moving the level of the PWT higher in the pot. This simply reduces the volume of soil available for roots to colonize. Containers with uniform soil particle size from top of container to bottom will yield better and more uniform drainage and have a lower PWT than containers using the same soil with drainage layers.

The coarser the drainage layer, the more detrimental to drainage it is because water is more (for lack of a better scientific word) reluctant to make the downward transition because the capillary pull of the soil above the drainage layer is stronger than the GFP. The reason for this is there is far more surface area on soil particles for water to be attracted to in the soil above the drainage layer than there is in the drainage layer, so the water perches. I know this goes against what most have thought to be true, but the principle is scientifically sound, and experiments have shown it as so. Many nurserymen employ the pot-in-pot or the pot-in-trench method of growing to capitalize on the science.

If you discover you need to increase drainage, you can simply insert an absorbent wick into a drainage hole & allow it to extend from the saturated soil in the container to a few inches below the bottom of the pot, or allow it to contact soil below the container where the earth acts as a giant wick and will absorb all or most of the perched water in the container, in most cases. Eliminating the PWT has much the same effect as providing your plants much more soil to grow in, as well as allowing more, much needed air in the root zone.

In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they starve/"suffocate" because there is insufficient air at the root zone to insure normal water/nutrient uptake and root function.

Bark fines of fir, hemlock or pine, are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as natureÂs preservative. Suberin, more scarce as a presence in sapwood products and hardwood bark, dramatically slows the decomposition of conifer bark-based soils. It contains highly varied hydrocarbon chains and the microorganisms that turn peat to soup have great difficulty cleaving these chains.

To confirm the existence of the PWT and how effective a wick is at removing it, try this experiment: Fill a soft drink cup nearly full of garden soil. Add enough water to fill to the top, being sure all soil is saturated. Punch a drain hole in the bottom of the cup and allow the water to drain. When drainage has stopped, insert a wick into the drain hole . Take note of how much additional water drains. Even touching the soil with a toothpick through the drain hole will cause substantial additional water to drain. The water that drains is water that occupied the PWT. A greatly simplified explanation of what occurs is: The wick or toothpick "fools" the water into thinking the pot is deeper than it is, so water begins to move downward seeking the "new" bottom of the pot, pulling the rest of the water in the PWT along with it. If there is interest, there are other simple and interesting experiments you can perform to confirm the existence of a PWT in container soils. I can expand later in the thread.

I always remain cognizant of these physical principles whenever I build a soil. I havenÂt used a commercially prepared soil in many years, preferring to build a soil or amend one of my 2 basic mixes to suit individual plantings. I keep many ingredients at the ready for building soils, but the basic building process usually starts with conifer bark and perlite. Sphagnum peat plays a secondary role in my container soils because it breaks down too quickly to suit me, and when it does, it impedes drainage and reduces aeration. Size matters. Partially composted conifer bark fines (pine is easiest to find and least expensive) works best in the following recipes, followed by uncomposted bark in the Note that there is no sand or compost in the soils I use. Sand, as most of you think of it, can improve drainage in some cases, but it reduces aeration by filling valuable macro-pores in soils. Unless sand particle size is fairly uniform and/or larger than about Â½ BB size I leave it out of soils. Compost is too unstable for me to consider using in soils. The small amount of micro-nutrients it supplies can easily be delivered by one or more of a number of chemical or organic sources.

My Basic Soils

5 parts pine bark fines

1 part sphagnum peat (not reed or sedge peat please)

1-2 parts perlite

garden lime (or gypsum in some cases)

controlled release fertilizer (if preferred)

micro-nutrient powder, other continued source of micro-nutrients, or fertilizer with all nutrients - including minors

Big batch:

2-3 cu ft pine bark fines

5 gallons peat

5 gallons perlite

2 cups dolomitic (garden) lime (or gypsum in some cases)

2 cups CRF (if preferred)

1/2 cup micro-nutrient powder (or other source of the minors)

Small batch:

3 gallons pine bark

1/2 gallon peat

1/2 gallon perlite

4 tbsp lime (or gypsum in some cases)

1/4 cup CRF (if preferred)

micro-nutrient powder (or other source of the minors)

I have seen advice that some highly organic (practically speaking - almost all container soils are highly organic) container soils are productive for up to 5 years or more. I disagree and will explain why if there is interest. Even if you were to substitute fir bark for pine bark in this recipe (and this recipe will long outlast any peat based soil) you should only expect a maximum of two to three years life before a repot is in order. Usually perennials, including trees (they're perennials too) should be repotted more frequently to insure vigor closer to their genetic potential. If a soil is desired that will retain structure for long periods, we need to look more to inorganic components. Some examples are crushed granite, pea stone, coarse sand (see above - usually no smaller than Â½ BB size in containers, please), Haydite, lava rock (pumice), Turface or Schultz soil conditioner, and others.

For long term (especially woody) plantings and houseplants, I use a soil that is extremely durable and structurally sound. The basic mix is equal parts of pine bark, Turface, and crushed granite.

1 part uncomposted pine or fir bark

1 part Turface

1 part crushed granite

1 Tbsp gypsum per gallon of soil

CRF (if desired)

Source of micro-nutrients or use a fertilizer that contains all essentials

I use 1/8 -1/4 tsp Epsom salts per gallon of fertilizer solution when I fertilize (check your fertilizer - if it is soluble, it is probable it does not contain Ca or Mg.

Hey...Do you know that becuase of you and this FREE info that you so kindly are sharing with us, the local nursery here wants to hire me to help educate their clients on how not to kill their plants!!lol
There are two workers there that want me to make them soil that is better than what they make!!lol
And to kick it off, the employees that have been there for a while, one guy in particular was amazed at how much I knew about container soil, that he asked me to come back and show him more. I think I will just print your info and give you the credit this time..lol
Thanks for everything you have done to my plants and once ignorant brain Al!!:-)

How cool is this!! Container the VI...unbelievable the excitement and interests this thread has generated.

Thanks to you as always, my plants are doing so well. Since I've started using this fabulous soil mix, I haven't killed any of my Jades/Succulents to root rot. I have never been succesful growing these before in the peat MG type soils that I used to use. Especially in FL in the summertime since we get a lot of rain for four months, I eventually lose them to root rot, very soggy soil. With this great Al's Soil Mix, all my plants, gardenias, potted Mango, Citrus, Christmas Cactus, I can go on and on...

Anyone out there that is hesitant to try this mix...TRY IT!! All of us here can't be wrong! I know that some of the ingredients are not the easiest to come by depending on your area, but once you find it...It is well worth the effort. I can't say enough good things about it.

Thanks again Al, for all your help and commitment, for sharing your vast knowledge with us on how to succesfully grow plants in containers.

One more thing!
I don't care how many people refute, or test, or try to diqualify this mix.
The only one that ever took the time to introduce a new phrase to me, "perched water table", something that I never heard of, nor my friends or family, not even nursery workers, the very thing that killed all my plant and theirs, deserves a thumbs up!!
After all these years, someone cared enough to educate us.
You even took the expense to send me crucial product to create happy vibrant plants with fruit and flowers!
Therfor I am a little bit partial towards anyone who gives such kindness with no expectations than to see one apply knowledge that benefits other humans in good ways..or need I say plants.:-). Knowledge they worked so hard to get, and freely shared.
That was you AL!!
Not the ones on this forum that knock this mix, make dispariging remarks about you or the soiless mix. Or e-mail me and try to criticize your criteria.
Therefor I am not a disciple, just a very appreciative member that for the first time in my life, enjoys unique and hard to grow plants from all over the world that at one time were impossible for me to grow.
Check out the water threads, and fertilizer ones too!
Mike

Having been a participant of the GW forums for a good number of years now, well before the departure of Spike and the acquisition by iVillage, I have to say that to have a thread(s) on a single topic generate so much response is unheard of!! Spike cut 'em off at 100 and I don't know of ANY that have generated a total of 700+ responses or comments :-)

And such a topic of continued interest and discussion! It pretty confirms the industry research that container gardening is the fastest growing subsector of the gardening/horticultural industry. It doesn't really matter where you are located or how much property you have or don't have - anyone can grow something in a container to provide an accent of color, something green and growing or a tasty bite.

And we all should give a HUGE thank you to Al for so generously giving of his time, knowledge and well-earned advise to make this activity so much more enjoyable and successful for us all. Thank you ((((((Al))))))) and congratulations on part VI. We should all have a big party when the count hits an even 1000 responses!

Now if we could just get him to stop with those morbidly compelling little "personal" tidbits that darn near gave many of his friends a heart attack thinking his family life was going down the tubes, life would be wonderful :-)

Awwww! Thank you all so very much. I get accused often enough for being more wordy than need be, so I'll just sum it all up and say that I am indeed so very fortunate for having gained the good will of such kind-hearted friends. Who WOULDN'T enjoy this place with people like YOU around? ;o)

It's great to see the appreciation that Al is receiving. We've been friends for several years, and have talked extensively about soils and their properties. My benefit, gardening in mostly shade, has been considerable. Water moves very slowly in shady conditions. Using the 'fast' soil mix allows me to water my containers without worrying about too much water remaining in the containers, which would cause root rot. Containers in shade are a challenge, and his advice has been helpful and illuminating.
Louise

Master Al, I am your humble student... I have listened well to your teachings, and I am a better gardener for having done so. I have shared your teachings with others in need, and though a few are slow to accept advice, I believe the majority who hear your words and try your way will see the difference with their own eyes. An entire school of students all praising your medium cannot be wrong!

How can we repay your generosity in sharing this knowledge? I think you would agree that "paying it forward" is the best way. Help thy neighbor to grow healthy plants!

The more I research, the more I find that bonsai masters have known these secrets for centuries, and have employed them to the benefit of their beautiful trees. So, how is it that most garden centers and growers are still using poorly aerated soils, and still teaching that a layer of drainage material in the bottom of a pot is necessary? These are outdated concepts, proven to be detrimental to container grown plants! I think greed is the underlying culprit.

I continue to spread your teachings where ever I go... to help those with rotting bulbs and poor root systems to see the light! I copy and paste your articles and recipes at will! There is hope for healthy plants... and its name is Al's Mix!

Thanks again, Al! I now feel confident enough in my knowledge that I'm mixing my own mediums and adding to my bulb collection, knowing that the majority of my gardening woes are things of the past!

Hi -
So I'm a convert to what Al has posted as being a good container mix. And I've read some on this forum so I hope at least I'm not asking obvious questions. Ok: so my questions:

1. I think I've read enough to understand that redwood chips are close enough to pine bark fines? I've seen the pictures Al posted, and it looks like a local HD has something close to what he his picture has at 9 o'clock. I also want to say that I saw a post by someone that I believed on a message that he has a friend growing in a mix of turface&redwood and it works very well though I can't find that message now. Alternatively: the local bulk distributor sells 1/4 inch chips of douglas fir...

2. Turface is sold at a shop a couple of cities over. The cost is a little more than I'd prefer, but worth it if there is nothing else that will work, though I saw a thread that said the was a product "play ball" that was a little cheaper (details? links?) and maybe pumice would work?

3. I've got some old Peat Moss (which I think that I could skip, but since I've already got it...) but it has totally dried. How do I rewet that stuff? I poured some into a bucket of water, and it just floats.

4. Crushed granite: haven't found it yet. I also saw a post a while back that said lava rock was a good thing? I found a good source of lava rock at bb size. Then also I found a distributor that sells them in 5/16 and 3/4 inch sizes? If those aren't good I'm plenty happy to keep looking... Or if anyone knows of a good bay area California source/link please let me know.

Mustard - you must be going to make the gritty mix & use it in plantings that will go a while between repots? The redwood chips should be fine if the size is appropriate. In large part, it's the size of the particles that makes the soil work well. The particles are of a size large enough that they hold no (or very little) perched water, but still small & porous enough that they have reasonably good water retention. I don't think I would use fir chips in the 5:1:1 mix, but because it would only comprise 1/3 of the gritty mix, it would probably be ok. I like bark best, and the best size for the 5:1:1 mix is sawdust to 1/4" pieces and partially composted, with most of the particles concentrated in the 1/16-3/16 size. I'm NOT suggesting you go out looking for bark that fits this description, but it will give you an idea of what works best.

The peat will eventually lose its hydrophobia & absorb moisture. You can make a dry soil in a wheel barrow or on a large tarp & mix it. Add water, mix, cover, and allow it to rest overnight & the water will diffuse throughout the soil & break its water repellency. It's actually best to make your soils a week or two ahead of time & keep them damp. This allows the reactive portion of the lime to stabilize pH and makes the residual lime more available.

BB size pumice? YOU DOG! ;o) I'd love to find a source for it around here. Again, if you are using pumice, the 1/16-1/4 size is best and if most of the particles are around 1/8", it's great. It's more porous than granite, but hopefully you read somewhere how to +/- the Turface and granite to reach your desired water holding ability (gritty mix). The larger sizes you found are probably too large.

I like the way jodik put it. Sometimes at garden centers when I bring the subject up about this kind of a mix, they look at me like I have two heads. But I just go on feeling good about what I have learned. And look forward to my flowers flourishing. filix.

I continue to spread your teachings where ever I go... to help those with rotting bulbs and poor root systems to see the light! I copy and paste your articles and recipes at will! There is hope for healthy plants... and its name is Al's Mix!

Glad you made it here...per Josh's suggestion! You will LOVE this fantastic(very affectionately) known as "Al's Soil Mix"!! You won't be sorry you go the extra mile to find all the ingredients...more importantly your Jades/Plants will love you for using it! Great Stuff!!

Welcome to the thread. It's the single best thread I've ever read on any gardening website and contains a ton of great information.

Last season I grew some Southwestern white pines in Al's gritty mix and some in regular MG potting soil as a comparison. While not a scientific study by any means, the pines grown in Al's gritty mix were at least twice the size in both height and in trunk diameter than the pines grown in the MG potting soil. I have not looked at the roots yet (the pines are all under at least a foot of snow at the moment) but this spring I will investigate the differences in the root systems and report back.

While at the local ACO hardware store today I noticed they had 40 lb bags of Shultz Soil Conditioner for about $13.00 per bag. I believe this is the exact same thing as Turface, just packaged by Shultz with a higher cost per pound. It did have the Profile logo on the front of the bag and was the same color (light brown) as Turface.

So if you want to try Al's gritty soil mix but can't find Turface you can also try the local hardware stores like ACO, ACE, etc.

The ACO hardware also had 40 lb bags of gypsum for about $5.00 per bag in case you are searching for that.

No pine bark yet LOL... a bit early in the season for bags of mulch in this area. Cabin fever setting in no doubt, but it will be a while since it's ony the start of February and we still have deep snow on the ground and bitter cold weather to come by weeks end.

No problem! Glad to pass along information like that for members who are having problems finding soil ingredients. It took me a long time to find Turface and the pine bark so I know how tough it can be!

I called the local feed store and they also had the crushed granite in 5 or 50lb bags. So if you need that be sure to call your nearest farm feed supplier. And make sure you are actually buying crushed granite, not oyster shells. Some feed stores sell shells for the same purpose. The granite I bought is black and white but there may be other colors of crushed granite as well.

I think the $12.99 per 50lb bag or Turface is standard, at least in this area when you buy it by the bag. Al might get a better price buying it by the pallet. =)

Not to make anyone jeolous, but I have to say that I am very fortunate to live just 20 miles from a nursery that actually makes potting soil Nd ships it to local nurseries..
That means that they actually carry the Bark Fines everyone here wishes they could find, the percursor to making soil! Mounds of it. They let me go there with my sifters, and even strain out the size bark that I need, and give it to me for free if it is under 20 lbs..Oops did I say free? :-)
Thanks again Dave for helping us...

Al,
My best friends father told me to thankyou so much for, teaching me the best kept secret for sucess with his Citrus Trees, that I was able to share with him!
He said he has never been able to grow healthy trees indoors up till now, until he used your soil I showed him how to make last year!!
He is so proud of his ability to enjoy his plants through winter now.
He says thanks so much! :-)
I say ditto!

My husband is a computer geek... and his tagline reads: "God made me simple, technology made me a god!"

As a gardener, I've stolen his tagline and changed it a bit... "God made me simple... Al's Mix made me a gardening god!"

Everywhere I go looking for ingredients to make Al's Mix, the clerks and employees look at me as though I had suddenly sprouted a second head, as someone above noted! Garden center and greenhouse employees alike are all brainwashed into thinking that organically rich, decomposing bagged peat soils are the only things plants will grow in, and they all look so terribly confused when you try to explain the concept of aeration in a container environment!

Yesterday, I was at one of the country's largest greenhouse supply companies,which just happens to be based here in my general area. The salesman had no idea where to find pine bark fines, and had no idea what constitutes a well-made medium! He sells soils and amendments for a living! Anyway... he said that if I could find a major supplier of the medium I needed, or of the ingredients to build that medium, he would try to order it all for me in bulk.

So now, my question is... who are the major suppliers or manufacturers of the main ingredients, and where are they located? If anyone has any information that might be helpful, it would be greatly appreciated!

Since I can find the grit ingredients most anywhere, I think the only ingredient I need is the pine bark in small particle form. If anyone knows a major manufacturer name or location, please spill the beans! :-)

Thanks!

And thanks to Al... I must agree that this is the single most important and educational thread I've ever read anywhere!

Yay! In January I finally found the right pine fines to use. Last year I bought something labeled as pine fines or Virginia fine pine and it turned out to be small mulch.

It was 68 degrees out today so I mixed up a fairly big batch for a balcony gardener. I figured out that the IKEA big blue bag works well for mixing soil. Same concept as the blue tarp only much smaller. It's about 3 feet by 1.5 feet bag.

I'm going to plant some peas once I get the lime to mix in.

I would echo the book concept. There are very few books on container gardening that discuss vegetables. Only two that I know of and I failed miserably using the "Incredible Vegetables from Self-watering containers" high compost mix. "Bountiful container" was good but sometimes I wanted more specifics. I ended up reading all of #5 and cutting and pasting the parts I thought would help me.

You could probably get some high school kid from a farm family to go through the posts and condense the useful parts. Don't know if you live in a farming area. Then next fall/winter as you are winding down the garden season you could edit it for the final touches.

So my questions are:
Are there different kinds of lime? And how do I get a smaller amount at a reasonable price? Not a 25 pound bag.

How big are the pine fines in your regular mix? The ones I got seem to be the same size as medium to large size perlite chunks. Dark brown color. Last year I bought ones that looked like they were 1/2" long x 1/4" wide by 1/8" deep. That is what I was able to screen out as the smallest particles.

How would you modify the mix for water loving plants in tall containers? I'm planning on starting a tomato plant outdoors in a 5 gallon bucket self-watering container. Then as the tomato plant grows, add cut off tops of other buckets. So I might have a total volume of 8 or 10 gallons by the time I'm done. 12" across and 3 feet tall?

Are there other occasions when you would modify the aeration/water retention properties? I remember some discussion that self-watering containers can handle vermiculite.

Someone posted on the thread #5 that you had suggested modifications for the "wick" in the self-watering container but I looked and didn't see it. Unless it was the rayon suggestion. What would you suggest for either a fabric wick or a soil wick?

How and why do you modify the basic mix for different plants? Being a newbie gardener, I don't know all the technical terms about plant types. Or how would you recommend modifying it for different climates? Say Arizona vs. Seattle.

I think I read that your old recipe for the mix contained less pine bark mulch. Something like 3-1-1 bark/peat/perlite and now it is 5/1/1-2? Why the change?

"Are there different kinds of lime? And how do I get a smaller amount at a reasonable price?"

There are many kinds of lime, but the hobby grower is best served with dolomitic lime (garden lime), which supplies both Ca and Mg in a favorable ratio - somewhere around 4:1, Ca:Mg.

"How big are the pine fines in your regular mix?"

I like partially composted fines, almost all of which will fit through 3/8 hardware cloth. I'm @ wk right now & don't have access to mo photo files, but I'll post a picture later.

"How would you modify the mix for water loving plants in tall containers? I'm planning on starting a tomato plant outdoors in a 5 gallon bucket self-watering container. Then as the tomato plant grows, add cut off tops of other buckets. So I might have a total volume of 8 or 10 gallons by the time I'm done. 12" across and 3 feet tall?"

I wouldn't change it at all.

"Are there other occasions when you would modify the aeration/water retention properties? I remember some discussion that self-watering containers can handle vermiculite."

I try not to sacrifice aeration on the altar of water retention in any of the soils I make for myself or others. Long term aeration is what the bark-based and gritty mixes have going for them. You may have to bite the bullet & water more frequently if you choose these soils to grow in, but in my experience, the gain is made manifest in increased plant vitality resultant from better root function/metabolism. If I do add something like vermiculite, it's usually in small enough volumes ("Someone posted on the thread #5 that you had suggested modifications for the "wick" in the self-watering container but I looked and didn't see it. Unless it was the rayon suggestion. What would you suggest for either a fabric wick or a soil wick?"

The 100% rayon chamois or strands from rayon mops work well. When you're watering via wicking, it's more important that the wick be very absorbent than if you're using the wick to drain perched water from the soil; you can use almost anything for that.

"How and why do you modify the basic mix for different plants? Or how would you recommend modifying it for different climates?"

It's more advantageous for you to water more frequently & retain the aeration/drainage inherent in either soil. If you need to modify it, you can add a little additional peat or vermiculite. Using fine bark instead of coarse, and the other strategies I mentioned while adding a wick to drain any perched water resultant from a smaller particulate size (until the planting has matured to the point it is no longer needed) would be my method of choice.

"I think I read that your old recipe for the mix contained less pine bark mulch. Something like 3-1-1 bark/peat/perlite and now it is 5/1/1-2? Why the change?"

I remember some discussions about the change 'way back when'. There was a typo or calculation error. You needn't follow the recipes exactly. I'm only giving you examples of possible recipes and discussing alternates to the peat-based soils, along with possible variations. All I'm really trying to sell here id aeration and durability. I know you'll be happier in the long run if you use a durable soil that retains ample aeration for the life of the planting. It could be made from ANYTHING - so long as meets these requirements and is not phytotoxic. ;o)

I have all my plants in your gritty mix. The 1/1/1 mix.
When I first transfered all my plants into the mix, gradually over time I started SIFTING out the small particles when I finally attained screens, until I finally got the perfect size and mix. All the igrediants about the same size as bbs's and a litter bigger.
I perfected the mix of course, when I only had two citrus trees left to plant though..lol

I put my "oro blanco" and my "calamondin" trees in the larger particle sized soil, while the rest were in the gritty mix I had started making with smaller particles from the start, not sifted, when I first heard of you and this thread on caintainers. It was new for me, even scary to do so. A soilles mix with no peatmoss? No way! I even protested. Remember?
I found myself, as above you had stated, watering these two more often, with the bigger particle sizes in the mix. I even complanied of them drying out to fast. Even now, indoors all winter, I have to water every other day.
Of course it is more work to keep up with watering, more than the ones that I only have to water once every week, some every other week.
All of my trees in both these gritty mixes are in 5 gallon plastic pots.

Well, to this day, not ONE leaf on these two trees I have to water every other day have lost one leaf, nor have had one problem since the summer. Not one! Nada!
The others, I have had some dropping leaves, and some yellowing, but they are still healthier than ever before!

Point?

I have chosen to have to water more often than to water less frequently. It is good for me..:-)
The two in the containers requiring frequent watering in same size 5 gallon containers are so much happier...I wonder why? :-)
Thanks so much for helping me make the gritty mix you suggested even better than when I started, perfect in size and in ingrediants for these two plants, and now for the others eventually. As for the others, I just have to watch my watering practices more often, in the smaller particle size gritty mix. I have to use a wooden dowel to make sure they have dried out, where as these two plants, I need nothing. It is still possible to over water in the unsifted gritty mix.
The larger partcle size one, I never have to worry at all WINTER or summer. I can water all I want...:-)

I think I am going to transplant all my other plants this summer, into the grtty mix with bigger particle size requiring watering more often. I want ALL my plants to be just as happy!

Does "2-3 cu ft pine bark fines" mean to use anywhere between two and three cubic feet of bark? Given that 1 cu ft = 7.5 gallons (I think), if you only used 2 cu ft that would be 15 gallons to 5 gallons of peat and 5 gallons of perlite, making it a 3:1:1 ratio instead of the 5:1:1 target.

Remember the recipe is just a guide or a starting point. The ratio of bark to other ingredients isn't something that is carved in stone. One of the recipes calls for 3 gallons of bark and a half gallon each of peat and perlite, which is 6:1:1. ;o)

My goal is to offer you an understanding of the attributes and drawbacks of a pretty broad range of potential soil ingredients, both on an individual basis and as part of the whole. I tried to write the article so you would be left with the knowledge of what MAKES a good soil. I'm not trying to sell you on what many refer to as 'Al's soil' - just on 'a' soil that's less expensive with better porosity and structural durability than what you can commonly buy in a bag.

If you understand what I wrote, you'll know that if the bark is coarse, you will want to add a little more peat, so perhaps a ratio of 3:1:1 might be more appropriate with a coarse bark than with partially composted fines. There are many other factors that enter into deciding on just how to make your soil. However it turns out, you won't be far off if you use a 5:1:1, a 3:1:1, or something in between. After you've seen how it performs, and when you go to make the next batch, you'll know almost exactly what you need to do to satisfy the unique requirements imposed by your growing style, location, plant material ..... If you're still unsure - no big deal - that's what we (myself, the other posters, and GW in general) are for. ;o)

I have been using "self watering containers" for the last three years with great success. Tomatoes, cukes & peppers. At the end of each season, I remove the fertalizer "strip" and combine the mix from my six or seven boxes to several larger containers for winter storage, clean the boxes and mend anything that is needed. Each spring, I remix, adding enough new potting mix (generic, store bought mix) to fill the containers, along with some cow manure and two cups of garden lime pellets per container. The question I have, can I keep doing this or should I replace the entire mix after a few growing seasons. Also, does the lime accumulate or does it "wash out" as the season goes along. You posted in your original thread:

"I have seen advice that some highly organic (practically speaking - almost all container soils are highly organic) container soils are productive for up to 5 years or more. I disagree and will explain why if there is interest."

Great thread and if this has been already discussed, please advise where I may find the discussion as I looked but was not able to find an answer.

From one of my '05 replies to the same question. It is a cut/paste job, so keep that in mind if you decide to read it:
In my estimation, the only case to be made for reusing container soils is one of economics, and you'll never find me argue against making that decision. If you can't afford it, you can't afford it. That said, and setting economics aside, you might decide to reuse soil for reasons other than economical. Perhaps the effort involved with acquiring (or making your own) soil is something you might not wish to go through or be bothered with.
In any case, it would be difficult to show that soils in a more advanced state of structural collapse can somehow be preferred to a soil that can be counted on to maintain its structure for the entire growth cycle. So, if the economic aspect is set aside, at some point you must decide that "my used soil is good enough" and that you're willing to accept whatever the limits of that decision might be.
All soils are not created equal. The soils I grow in are usually pine bark based & collapse structurally at a much slower rate that peat based soils, yet I usually choose to turn them into the garden or give them over to a compost pile where they serve a better purpose than as a container soil after a year of service. Some plantings (like woody materials and some perennials) do pretty well the second year in the same bark-based soil, and with careful watering, I'm usually able to get them through a third year w/o root issues.

Watering habits are an extremely important part of container gardening. Well structured soils that drain well are much more forgiving and certainly favor success on the part of the more inexperienced gardeners. As soils age, particulate size decreases, water retention increases and growing becomes increasingly difficult. If your (anyone's) excellence in watering skills allows you to grow in an aging medium, or if your decision that "good enough" is good enough for you, then it (your decision) is good enough for me, too.

The phrases "it works for me" or "I've done it this way for years w/o problems" is often offered up as good reason to continue the status quo, but there's not much substance there.

I'm being called away now, but I'll leave with something I offered in reply on a recent thread:
"... First, plants really aren't particular about what soil is made of. As long as you're willing to stand over your plant & water every 10 minutes, you can grow most plants perfectly well in a bucket of marbles. Mix a little of the proper fertilizers in the water & you're good to go. The plant has all it needs - water, nutrients, air in the root zone, and something to hold it in place. So, if we can grow in marbles, how can a soil fail?

Our growing skills fail us more often than our soils fail. We often lack the experience or knowledge to recognize the shortcomings of our soils and to adjust for them. The lower our experience/knowledge levels are, the more nearly perfect should be the soils we grow in, but this is a catch 22 situation because hidden in the inexperience is the inability to even recognize differences between good and bad soil(s).

Container soils fail when their structure fails. When we select soils with components that break down quickly or that are so small they find their way into and clog macro-pores, we begin our growing attempts under a handicap. I see anecdotes about reusing soils, even recommendations to do it all over these forums. I don't argue with the practice, but I (very) rarely do it, even when growing flowery annuals, meant only for a single season.

Soils don't break down at an even rate. If you assign a soil a life of two years and imagine that the soil goes from perfect to unusable in that time, it's likely it would be fine for the first year, lose about 25% of its suitability in the first half of the second year, and lose the other 75% in the last half of the second year. This is an approximation & is only meant to illustrate the exponential rate at which soils collapse. Soils that are suitable for only a growing season show a similar rate of decline, but at an accelerated rate. When a used soil is mixed with fresh soil after a growing season, the old soil particles are in or about to begin a period of accelerated decay. I choose to turn them into the garden or they find their way to a compost pile.

Unless the reasons are economical, I find it difficult to imagine why anyone would add garden soils to container soils. It destroys aeration and usually causes soils to retain too much water for too long. Sand (unless approaching the size of BB's), has the same effect. I don't use compost in soils because of the negative effect on aeration/drainage. The small amount of micro-nutrients provided by compost can be more efficiently added, organically or inorganically, via other vehicles.

To boil this all down, a container soil fails when the inverse relationship between aeration/drainage goes awry. When aeration is reduced, soggy soil is the result, and trouble is in the making."

I don't grow in SWCs, so I don't claim any amount of expertise beyond what also applies to conventional containers. The fact that you don't water from above does reduce impact of that practice.

Yes, added lime accumulates. At first, lime is reactive & neutralizes acidity in soils until an equilibrium is reached. Then it becomes residual. Anything that is dissolved in water raised the level of TDS (total dissolved solids) and EC (electrical conductivity). The higher these levels are, the more difficult it is for plants to absorb water and the nutrients dissolved in water. Our goal should be to keep o/a TDS/EC as low as possible while still keeping each of the individual nutrients in that range between adequate - luxury levels.

Residual fertilizer and lime in used soils raise TDS/EC and make our fertilizing decisions much more critical. If, e.g., you used a high P fertilizer, have residual lime or fertilizer in the soil, or a combination of any of these, you could easily have a soil that is near the upper limit of what is a favorable level of TDS/EC and still have nutritional deficiencies. IF a deficiency shows up, how can you add anything to the soil w/o risking elevated TDS/EC and associated fertilizer burn?

Great post Al. What an education you've given all of us via this thread and it's predecessors! Thanks for sharing your knowledge, wisdom and experience.

I'm getting ready to build some of the gritty soil mix and will add in some gypsum as you've suggested.

Question: Is there any reason to add additional gypsum later in the year as a top dressing or is it strictly added to the soil when mixing it?

Also, what about plants (conifers in my case) who might grow for two years in the same container and soil. Will the gypsum break down like a CRF and need to be replaced?

BTW, for anyone looking for gypsum, I found this interesting. The local hardware store sells 40 pound bags of gypsum for about $6.00, while the local garden center sells a 5 pound bag for $5.00. I see whey it pays to buy in bulk!

Dave - I've never had to add lime to the 5:1:1 mix or gypsum to the gritty mix, but I suppose it depends on how long you employ them, the pH of your irrigation water and how much Ca/Mg is in it, and even to some degree - what plant material is planted in the soil; but then, I usually turn the 5:1:1 mix into the garden or compost after a year, and the gritty mix after 1-2 years, which has a bearing on availability.

Usually, the best way to determine if you should add is to watch newly emerging growth after the first year in the soil. If you see signs of a Ca deficiency (particularly watch for distortion in newly emerging leaves) - add gypsum or lime if you observe it. This doesn't work particularly well for conifers because of how the leaves emerge, so if you want to scratch a small amount of gypsum into the soil after the first year, it probably wouldn't hurt anything.

Just remember that no matter what you add to the soil, if it dissolves it raises EC and TDS levels, making it more difficult for the plants to absorb water and nutrients. While a slightly superfluous application of lime or gypsum might be unlikely to harm the plant, it does reduce the amount of fertilizer you can safely apply and reduces the safety margin between possible individual deficiencies and plasmolysis (fert burn). Adding unnecessary solutes also makes fertilizer choice (NPK %s) more critical in avoiding deficiencies.

Alice - I've never experimented with using antacids as a Ca/Mg source. Dolomite is very inexpensive and has a favorable Ca:Mg ratio, so I'm content with that for now. You would have to do the research to see if it would work (I doubt it would work as well, but I really don't know) and from a $s perspective, I'm pretty sure it's not economical. $2-3/oz vs .15-$1/lb .....

Al, thanks for the post. Basically sounds like I should go ahead and add the gypsum to the gritty soil components when I mix the soil at the start of the season and not worry about adding it later in the season. I just didn't know if it was like the CRFs that tend to be used up late in the growing season.

I'll probably only go one or two seasons at the most before potting up these small conifers so maybe I won't ever have to worry about adding gypsum suppliments. I want to make sure the soil mix is free-draining rather than clog it up by adding unnecessary additional gypsum during the growing season.

If you only need a couple teaspoons of lime you could hit up your local horse farm for a cup or so. Many horse farms use lime to remove the urine smell from the wet spots in the stalls. Unless it's a different type of lime?

That would be different. It's hydrated lime or Ca(OH)2, aka calcium hydroxide. It's very caustic and can rapidly raise pH. It should probably be left to the pros or the very experienced hobbyists. It's almost never knowingly used by hobbyists. Incidentally, it also shouldn't be used with fertilizers like FP 9-3-6 that have a fair % of their N in nitrate form or with slow release fertilizer products because it reacts with these products to produce ammonia gas which will readily burn roots. Thanks for the idea, though. ;o)

Today, I went to the only nursery in my area that I can get bark fines from.. I was able to sift out 4, 20 gallon buckets worth, which made me feel like a kid again, climbing all over that mountain, when one of the owners approached me in the storage garage where they keep it all so it would stay dry and asked me what I was doing..
This beautiful sweet pine smelling mound must of been at least 15 feet high by 40 to 50 feet long. To me it looked like a mound of "gold", a precious resource hard to find. I was in "fine bark" heaven. I kept thinking of how happy my plants would be, and most of the members here if they could see what I saw...
Anyway, when the owner asked me what I was doing, I tried to remember all these threads and all Al shared with us, the best I could.
I shared with him as much info on soil and water retention and how to make the gritty soil my favorite..
He was in shock at how much I knew, and couldn't believe that he never thought of a better soil to make, since he had access to all the ingrediants, to help his wife grow her plants, along with his citrus, without the fear of overwatering...
He was so interested and excited in what he heard, especially in trying the gritty mix, along with the 5.1.1.mix, that he started sifting the fines with me..lol
In the end, after all the fun I had in collecting this "gold" with him, he let me leave the place with all those buckets for free, along with a shoe full of sifted pine fines!
The sad part though was, when leaving there, I felt a little guilty , because it should of been Al getting all this "gold" for free, and not me....

Without fanfare, you need to take a good part of the credit for advancing your knowledge and skills too, Mike. No one force-fed you. You sought out the info from plenty of sources here on GW. I wasn't the only one who helped you along, I'm sure. All the others who participate on this & other forums deserve the same 'attaboy' you gave me. ;o)

Just as a devil's advocate here... One of the organic gardening books referred to "in-ground hydroponics" as a negative term for traditional large-scale farming. The soil only exists as a growing medium and all the inputs get fed in by the farmer.

Along similar lines I've heard that organic farming can come close to the yields of conventional production. But that is only after several years of letting the soil rebuild itself and getting the beneficial insects settled.

So is Al's method similar to the "hydroponics" method? Are there ways to get "sufficient" growth from reusing soil with less synthetic ingredients?

Is this method similar to competing for the largest vegetable at the county fair?

One of my original motivations for gardening was to help use the earth's resources more effectively by growing my own food. So if I'm buying fertilizer made from petroleum-based resources and not reusing the soil that's just another way to waste resources. Better off to expend less effort and just keeping buying veggies that go bad in the fridge.

So does anyone have any thoughts on this?

In reality I'm going to be using the pine fines approach. I may tweak it a little just to use the tons of different fertilizers I already have. Synthetic, Organic and CR. I'll see how well it works with self-watering containers. Probably throw in a little compost to the tomatoes, since I have that leftover from last year. And high PWT isn't as much of a problem in a 2 ft high container for a thirsty plant. And trying to stretch the seasons indoors.

If the soil is not suitable for crops the following season in containers, it will still make a wonderful amendment or base for raised beds, or to mulch, etc... No one suggestion throwing it out completely.

For SWC use, justaguy has suggestions (I think it as him) that seem to be working for me too. I ended up mixing in more sphagnum to the tune of oh... 3:2:1.5 (bark:sphagnum:perlite) and in 18g rubbermaids, I get enough moisture on the surface to direct sow. (my peas are going NUTS in this mix. they love it.) So yeah, for SWC you might need to make small adjustments.

Hi, Alice - You asked "So is Al's method similar to the "hydroponics" method?"

ALL container culture is much closer to hydroponics than it is to growing in the garden. We regularly flush the soil with water and add nutrients as required, just like in hydroponics. The soil physics and chemistry are markedly different as well. The physics are discussed in this thread, and the chemistry is different from mineral soils in that we need to take responsibility for insuring that ALL the necessary nutrients are available in the soil, preferably at all times and in a concentration range that is high enough to prevent deficiencies, yet low enough that plants don't have difficulty absorbing water and the nutrients dissolved in it.

"Is this method similar to competing for the largest vegetable at the county fair? If you're asking if you'll ever win a prize for the biggest 'anything' if it was grown in a container - it's not likely. There are several reasons for that, but I won't go into it now. You CAN grow good yields of tasty food and ornamental plants in containers though. It's a science, just like growing in the ground is a science - just a few different rules and quirks you need to take into consideration as you go.

I can't help you much with your should I/shouldn't I dilemma because it's a personal decision. I can say though, that in my experience it's much more difficult, especially for someone inexperienced, to get that whole 'compost/leaf mold/ only what I can find in my back yard' thing working well enough to ward off frustration. EASY (in a conventional container) is a fast soil and a good soluble fertilizer, but I understand if you choose not to go that route.

I don't know if I answered all your questions or not. If not, there is room for more in the box right under the last reply. ;o)

Good science in adopting Al's mix versus the local stores' bagged soil mixes. Interesting how this thread is approaching the fringe between container gardening and hydroponics/aeroponics. One hydroponic method uses a bucket of 8 to 16 mm expanded clay balls with a water / nutrient solution dripped through it. This may be the closest comparison. As soil-less aeration models are considered, aeroponics with roots exposed completely to air in a dark chamber with a water / nutrient fog has shown some of the quickest growth rates for plants in comparison to any other mentioned methods. In aeroponics, the roots will die should the nourishing mist ever stop for an extended period of time. Of note, some aeroponically-grown plants will produce more fruit or tubers, but at a smaller size. Backing down the ladder, there is a deep water culture bubbler bucket. In this setup, the plant roots are mostly submerged in highly-aerated nutrient water, which provides large water-thirsty plants with all the water and food they need. The roots exposed to air help the plant, while the aeration in the water keeps the submerged roots from dying. This is a fast grow method that can be used for big plants. Al's mix is much easier for the casual gardener, as the bubbler bucket requires checking the EC and pH daily, topping off water as it is used in the bucket, and replacing the nutrient solution on a regular basis. Also, the hydroponic techniques typically run better with a higher grade nutrient, such as the one from General Hyrdonics. Note that this nutrient changes to meet the different stages of a plant's life. Al's containers can be used with nutrient water that 'runs to waste' with some being retained in the Al's mix for use by the plant between 'waterings'. This fits better with demanding schedules. I mention the above for illustrating that different grow techniques exist for different growers. Everyone needs to find something that fits their skill level, time, money, and performance needs. I have hopes for doing some comparisons this summer with a few different garden plants.

Some interesting points & info, DR. Thanks. Hey - I just gave you some impressive credentials. ;o)

I think that on a scale of 1-10 with 1 being the equivalent of growing in the garden, and 10 being a totally hydroponic set-up, container culture in general is probably around a 7-8 - much closer to hydroponics than garden in the earth. Many, if not most gardeners really need to be reeducated because they want to bring everything they learned about gardening in the earth to container culture, and much of the information/technique just doesn't work. I know I have faced some pretty stiff opposition from people who probably had great skills in the garden & felt that all they learned should apply to container culture, but as we are all learning, much of it doesn't.

I know a lot of people twice my age that grow in pretty much nothing but dirt & manure and sometimes it's hard to have a conversation about what we are growing. It's especially sensitive when their container plants don't do well in soggy mushy dirt - and they blame the containers or the plants.

Does this mean that one has to learn the science behind hydrponics in order to be truly sucessful in container growing, especially in the gritty mix?

I have been to a store where they sell hydroponic materials and supplies, and always stayed completely away from that kind of gardening, because I never thought I could have the time nor have I ever been interested in growing that way.

If I am growing happy plants all this time, then I must being doing something right, especially with the fertilizer regimand.

But how come, none of my palms were happy in the gritty mix?

I took them out of the gritty mix last fall, and they are growing better in the 5.1.1 mix with peatmoss? They are responding much better.

Confused about this one as regards my palms. I thought the gritty mix was good for ALL houseplants?

"Does this mean that one has to learn the science behind hydrponics in order to be truly sucessful in container growing, especially in the gritty mix?"

Of course not. ;o) Lots of people are happy with their results, even if they are only making a half-hearted effort or growing in unsuitable soils. I didn't say that to be disparaging, only to point out that contentment with the fruits of any labor is a very subjective thing. You obsess - the other guy says, "Ehh - who cares? ...good enough for me." Both are successful according to their standards. The difference lies in who wants to be MORE successful, and the acquisition of additional knowledge can rarely be considered an impediment to that endeavor.

"But how come, none of my palms were happy in the gritty mix?"

I don't know, but it's unlikely it had anything to do with the soil, if it was close to what I've been using. I've never seen a plant, out of the thousands I've grown, that wouldn't take very well to it. I would be thinking of cultural issues like watering/soil moisture levels, nutrition (toxicity/deficiency - fertilizer type/formula), light, temperature, before I would suspect the soil.

Several palms have unique requirements for optimal growth. I have been growing a Majesty Palm in a container for around 4 years, and what might be either Washingtonia robusta or Washingtonia filifera in a container for around 2 years. My container soil contains a lot of peat and perlite with weak slow realease fertilizer. Soil collapse has brought me to repot the Majesty Palm three times since I purchased it. These are kept in my office with overhead fluorescent lights and a west-facing large window. Be prepared to cringe when I tell you that despite the fan-leaved palm having a drain hole and saucer, that the Majesty Palm has NO drain at all. This is NOT optimal, but it helps to keep the palm from growing too quickly. I have already had it consume 1/3 of my office before attacking it with pruners. The reason this method works is that I accept the less than optimal condition and water based on plant response and soil condition. My containers are around 20" diameter and keep the perched water table lower in the pot with the large volume of container mix. The top of the containers would appreciate a light mulch to conserve moisture on the surface layer. I use a Maxicrop seaweed extract for micronutrients and a light application of slow-release fertilizer on the surface of the container mix. I avoid over fertilizing and find the palms do quite well.

"Ferilizer guides recommend a 4-1-6-2 Mg (N-P205-K20-Mg) ratio fertilizer (for example, a fertilizer marked "8-2-12-4 Mg"). The nutrients N, K20, and Mg should should be included in equivalent percentages in controlled-release form. Because palms are highly prone to several potentially fatal micronutrient deficiencies, any fertilizer applied to them should contain 1 to 2 percent iron and manganese, plus trace amounts of zinc, copper, and boron, to prevent deficiencies."
source: Florida educational site

Because I am a blessed individual who still has a job during this recession, I am doing the work of the two other people who were not as fortunate. If time allows, I will be switching my palms over to a faster draining mix with drainage properties like the gritty mix. While I can not offer you any experiences on growing palms in containers of gritty mix, I have enough observational data to respectfully believe that the gritty mix in and of itself might not be the source of your issues.

I don't know if the message came across wrong. I was trying to be thought provoking.

I can definitely see how most of the existing plants I have aren't in the best soil. I tried buying pine fines last year but ended up with bark mulch that wasn't aged and wasn't particularly small either.

I think soil-reuse for me will partially be an issue of logistics as well as economics. I can't see getting a full 24" container off a balcony through the living room and down a flight of stairs. I'll see what works. Everything will get emptied whenever I move out of this apartment I'm sure.

I don't have a good place to put the soil either. I've just been going outside the apartment and dumping it onto the area between the parking lot and the fence. Most of the soil I have now definitely is not worth re-using.

If I go with the continuous replanting concept in some containers I may not have a chance to change out the soil. Or with overwintering plants. The tomato plant that was being brought inside to finish the last green tomatoes is still alive. It is getting yanked this weekend.

In ground isn't an option for me right now. I saw my mom doing community garden plots 25+ years ago and I don't think I'd want to do it even if it was available. I remember endless trips back and forth to the car carrying milk jugs full of water.

From what I've heard SWC's are the way to go for certain vegetables anyways. Much easier consistent watering for tomatoes.

I'm finding container culture to be very easy, now that I've educated myself to the vast differences between gardening in the ground, and gardening in a pot. The two environments are like night and day!

I've found that a more inorganic approach works much better for containers... and takes the guesswork out of much of it. In the ground, Mother Nature takes care of things, keeping a balance of good and evil, so to speak.

I'm still having a difficult time finding local pine bark fines... but other than that, I'm on a roll! My plants look healthy, and are responding well to Al's Mix... and some of my bulbs are rather picky!

I remain a student of the "Approach To Better Container Gardening Through Al"!

Alice in Virgina,
I do find your comments 'thought provoking' and am glad to 'hear your voice' on this forum. I hope to see more of your input and learn from your personal experiences.

Regarding your growing situation, it sounds like you have an elevated balcony suseceptable to winds, possibly lack of humidity, and a watering challenge. I am not sure if you are using city water, but personally I am treating my city water to neutralize some of the chloramine additives that the city uses. Additionally, you have already mentioned the challenges of getting materials up and down stairs.

As you have noticed, after time some container mixes are ready for disposal. Non-organic and synthetic soils are long-lasting in comparison. These additives tend not to hold water or nutrients as well as organic mixes in general. Another issue with the non-organic and synthetic soil ingredients is that watering frequency will differ from the typical bag of potting soil. More importantly, when you lose the benefits of organic, more-interactive, soils, feeding the plants becomes more dependent on you to provide water and nutrients in a solution that is pH adjusted and not too high in disolved solids. The pH of your water and/or water and nutrient solution should be a little lower than what you would use when growing in-ground. Typically, a pH of 5.8 is a good starting point.

You mentioned that you have a method that works for you. That is wonderful! Gardening should be a combination of what works for you and what to try, the 'Next Step'.

You mentioned wanting to try self-watering containers, which leads me to believe water management is an issue. On your balcony, running excess water off the balcony could possibly offend someone below. ; ) Also, your options could require some technical engineering, such as setting up a water barrel with a pump on a timer and drip lines to your containers. Should you work outside your home, then I understand the widely varying weather conditions could lead to wilted, overheated plants, when you return home. Using containers with larger volumes, mulch layers on the surface, and container mixes with more surface area are ways of keeping a higher moisture level. Wind protection would benefit your plants too.

I hope that my comments are amiable, and would welcome you to contact me about your palm issues either on this forum or by going to my page and emailing me confidentially.

I know that you've advised against using hardwood bark in your mixes, but the best option that I've found for your 5-1-1 mix is a clay soil conditioner that's composed of age pine and/or hardwood bark and gypsum. I can see traces of leaves in the bags that I've purchased, so I suspect that they contain some (if not all) hardwood bark. Would you consider this to be suitable for short-term plantings (one year or less), or is it likely to break down too quickly? Would I better off with fresh pine bark fines?

Also, for your gritty mix, I'm having trouble finding the oft-recommended gran-i-grit (all of the local feed stores sell the oyster shell grit instead). A local landscape supply offers 3/8" crushed stone. I assume that it will provide a little less overall surface area than the the smaller gran-i-grit grower (and, hence, less water retention), but are there any other downsides? Alternatively, I've wondered about substituting more Turface for the granite. In the heat of summer, the added water retention is likely to be an asset.

Hardwood bark can be used, but has it's issues: Here is a cut and paste with link to follow:

Hardwood Bark

Deciduous hardwood bark is used extensively in many areas of the country as a container media amendment. In Florida, hardwood tree species are grown primarily in the northern third of the state. Hardwood bark differs greatly from pine bark in its chemical and physical characteristics. The pH range of fresh hardwood bark is 5.0 to 5.5. As the bark ages in the presence of water, the pH increases to 8.0 or 9.0, a condition much too alkaline for plant production. Fresh hardwood bark should never be used immediately for potting plants.

Researchers at the University of Illinois developed an effective composting procedure for hardwood bark in the 1960's which effectively adjusts the pH and pasteurizes the bark, eliminating most soil-borne pathogens. Prior to composting, hardwood bark has two other features which render it unfit for plant production. Because hardwood bark decomposes more rapidly than pine, there is initially a high demand for nitrogen by microorganisms which will induce a nitrogen deficiency in plants growing in the fresh bark. The second potential problem relates to certain hardwood species which have been reported to have a phytotoxic effect on plants grown in fresh bark or plants drenched with extract from fresh bark.

Hardwood bark should be mechanically processed to small particles which will pass through a 1/2-inch (1.27 cm) mesh screen, with 10 percent of the particles larger than 1/8-inch diameter and 35 percent less than 1/32-inch (0.8 mm) diameter.

Composting procedures as prescribed by the University of Illinois researchers specify that for each cubic yard of a 2 parts fresh hardwood bark: 1 part sand (v:v) mix the following should be added: 6 pounds (2.7 kg) ammonium nitrate, 5 pounds (2.3 kg) superphosphate, 1 pound elemental sulfur and 1 pound iron sulfate. These materials should be blended in the medium thoroughly, preferably in a tumbling type mixer, and arranged in large deep piles, kept at approximately 60 percent moisture. Covering the pile with a plastic sheet will help stabilize the moisture content during the composting period. The high level of microbial growth in the presence of the fresh bark and fertilizer causes the temperature to approach 150°F (66°C), a temperature which eliminates most pathogens. Turning the pile of composting bark 3 to 5 times during the 60-day process is recommended to get a uniform product. After composting, bark-induced nitrogen deficiency problems and phytotoxicity caused by bark from certain tree species are eliminated.

Shazaam - I don't use hardwood bark/sapwood because it breaks down quickly and there is often considerable N immobilization associated with its use. I think I outlined the reasons for choosing conifer bark over other wood products in the OP, but all the decisions are up to you. ;o) You asked if you would be better off with fresh PB fines, and I would say 'yes'.

You don't say where you live in your user info, but I'm thinking you probably live near a coast. Oyster shell is not a suitable substitute for the grit, but if you can't find grit, you could try screening the Turface through an insect screen, retaining the large particles, & using 2 parts screened Turface + 1 bark pine bark. Did you try the elevators near you for the Gran-I-Grit?

Thanks for the quick and helpful replies. I don't recall what first brought me to this forum a few months ago, but it has quickly become my favorite...in large part because of what I've learned from the two of you.

The bark in the soil conditioner would be better described as composted than aged. It appears to have been composted to a point similar to the description in the article you quoted, justaguy2, so I'm inclined to say that N immobilization isn't a major concern. That's a guess, of course, because I have no information about the methodology of the process. Nonetheless, the more I think about it, the more I realize that it might have been too thoroughly composted to be appropriate for this particular use.

You clearly made a good case for pine bark in the OP, Al. I think I just got a little to excited over this product -- it's the only aged bark that I've been able to find (I recall that you prefer aged pine bark for the 5-1-1 mix)and it might contain pine bark, so I think I latched on to it and little too quickly. I'll go ahead with the fresh pine bark for now, and I'll plan on making a pile in the backyard (mixed with a high N organic fertilizer) so that I have aged fines in the future.

As for my location, I'm near Charlotte, NC. North Carolina Granite isn't that far away, but they only sell gran-i-grit by the pallet (and they were unable to point me to local retailers). The only local source that I've found so far is Tractor Supply -- they can order granite grit for me, but their price is a ridiculous $6.25 for a 5 lb bag. When you say elevators, do you mean something like a bulk livestock feed supplier? If so, I'll look into it -- I've exhausted the farm supply category in the local yellow pages, though, so I'm not quite sure where to turn.

Late night ponderings..., this thread is very focused on the selection of a container mix that is long lasting, well-drained, and highly aerated, with the rule that the container mix does not negatively impact plant health. This is a very worthwhile goal. However, with the thread title of "Container Soils - Water Movement & Retention", I would like to see more written about water delivery methods for deploying and maintaining moisture levels over the different life stages of various plants from germinating seeds to heavily-canopied, large-fruited plants. To make this more interesting, the widely-varied micro-climates should be considered with regard to temperature swings and spikes; sunlight levels; drying winds; and other unpredictable environmental factors.

As for my location, I'm near Charlotte, NC. North Carolina Granite isn't that far away, but they only sell gran-i-grit by the pallet (and they were unable to point me to local retailers). The only local source that I've found so far is Tractor Supply -- they can order granite grit for me, but their price is a ridiculous $6.25 for a 5 lb bag.

Call them back and hope for a non moron. They are wholesaling and they know exactly who their customers are. Telling you who they are is good business. The most frustrating part of making your own mix is finding the local suppliers. They exist, but they aren't always the easiest to locate initially. Stick with it and pretty soon you have a go to source for everything as well as a backup source.

I would like to see more written about water delivery methods for deploying and maintaining moisture levels over the different life stages of various plants from germinating seeds to heavily-canopied, large-fruited plants. To make this more interesting, the widely-varied micro-climates should be considered with regard to temperature swings and spikes; sunlight levels; drying winds; and other unpredictable environmental factors.

Well, let's discuss this.

First we have Al's 5-1-1 mix and then we have the gritty mix.

The 511 mix is 5 parts pine bark fines, 1 part Perlite and 1 part peat. The gritty mix is 1 part Grit, 1 part grit and 1 part bark.

Neither of these mixes is going to be optimal in 100% of all cases, rather they are very good mixes for a wide variety of applications.

If your goal is to find the right mix for your climate to grow a Sunshine Blueberry all year indoors and outdoors from 2 year old plant to 20 year old plant then you need to read between the lines a bit.

Let's consider all of the ingredients in the 2 'Al's' mixes'

1. Peat
2. Pine bark fines
3 grantite
4. Perlite
5. Turface MVP

Of all the ingredients peat will break down the fastest.
This increases it's water retention and minimizes it's air holding capacity.

Pine bark is much like peat. It is acidic, breaks down fairly quickly and becomes difficult to rewet if it get's too dry. The major difference is it breaks down much more slowly than peat.

Granite holds little in the way of water or nutrients, and the same is true of perlite. Granite is more structurally sound (will last longer) than perlite.

Turface is the wild child. It won't break down, it holds a lot of water (though not as much as peat or bark), it holds on to nutrients better than most potting mix ingredients and it provides good aeration.

Take these factors into account and one can build their own potting mix.

Mature plantings which require large amounts of water will do best in something along the lines of a 511 mix. Houseplants, succulents, and perhaps even citrus tree will do best in something approaching the gritty mix.

All sorts of variations can be made once on understands why the 2 'Al's mixes' are what they are and contain what they do.

It may surprise some, but I have never made either of the
'Al's' mixes. Does this mean I don't think much of those mixes? Good grief no. I think those mixes are very solid.

Rather, I understand what plants need and why, think the ingredients are sound and so mix and match according to my needs/preferences.

As one example I am seed starting. I have no peat on hand so my seed starting mix is bark and turface.

Do I need the peat? Not really. The bark is well composted. If it wasn't I could increase the turface and not screen it.

If it wasn't so well composted I would value the peat.

Likewise I don't haven any containers with granite in them.

I just screen the Turface or use perlite instead. Either way reduces water holding capacity,

I do what I do in Wisconsin. For hotter, more arid climates find ways to increase the water retention while not significantly losing aeration.

Don't copy mixes. Understand, instead, why a mix is what it is and adjust for where you are and what you grow.

I do the same... I use Al's recipes as a base or starting point, and I add or subtract ingredients and amounts of ingredients depending on what I'm planting and where it will be located, indoors or out. Al's Mix is wonderful as is for my Clivia and bulbs, but other plants need a little something different.

I think the "why" is extremely important! We need to know why we're using a certain medium, or what's the point?! Once I understood why I needed to find a better medium, and why a more porous, inorganic approach would work better, everything fell into place.

In place of the turface, I understand that certain oil dry products, akadama, and certain cat litters could be possible substitutions. I believe NAPA sells a cheap oil dry product that holds up well in a medium... and certain diatomite, or fired clay cat litters can be used. I, myself, will have to resort to the oil dry as some of the grit ingredients aren't available to me. And I'm having a heck of a time finding a soil conditioner made of pine bark fines!

justaguy,
Nice post. Another variable to consider would be the weight. I use larger volume containers that are relatively fast draining, but because of volume hold a large amount of aerated and moist container mix. This allows the plants to get the oxygen they need and search out by root penetration into the moisture for some of their increased water needs.

I also like the larger containers for when the summer heat begins to cook the containers and shut down the plants. As such, when blending new container mixes, I would like to calculate the weight to avoid creating immovable back-breaking containers. A side note on heat, while the darker containers are great in spring, the lighter-colored containers are better for the soaring temperatures under a noon sun.

Regarding the 5-1-1 or gritty mix, the gritty mix appears to have higher aeration properties. From what you have said, would it be better to use the gritty mix outdoors with water loving plants and water more frequently? With the advances and ready-availability of garden hose timers, watering 2 or more times per day is possible. I find that drip lines can clog and soaker hoses will water irregularly along their length. Also, I no longer have the time to go out every day to hand water. Also, in a 24" diameter container on a breezy day, it is difficult to water evenly across the entire surface of the container. Should you have found a better way to water, please share.

I realize that misting systems can help with humidity and temperature. Still, while I am not as concerned watering outdoors with water spillage as I am indoors, neatness still counts. I do not need puddles on my walkway or entrance. Also, I have enough iron in my water that getting water on my house, entrance, or walkway would leave orange iron stains.

You mention making your own mixes. Have you tried any of the following combinations? If so, what did you think?

1. turface and granite
2. turface and perlite
3. granite and perlite

And, do you find your self using the 5-1-1 style mix in small volume outdoor containers, while the gritty style mixes are more user friendly in larger outdoor containers?

Hi all. While at the hardware store over the weekend I bought a small bag of Oil-Dri and picked it up to try for a possible ingredient in Al's "gritty mix" container soil. This was a 10 pound, blue and white paper bag manufactured by the Oil-Dri Corporation of America, so it wasn't a generic "oil drying" product. The bag didn't specifically say what the product contained or how the product was manufactured, but for $3.00 I decided to try it. The bag even had a photo of a garden plant, stating that you could use the product for container gardening.

The Oil-Dri product visually looks good, lots of gray and brown earth tones, and would look good in a container. It also has a good particle size for the gritty mix. The particles were very hard as I could not break them with my fingers.

I scooped out a few cups of Oil-Dri, sifted out the fines, and placed a small amount of product in two different plastic containers. Then I added water to both containers and performed a "soak test". Once container was left outside where it would quickly freeze due to cold temperatures and the other container was brought inside to sit at room temperature.

After 48 hours of soaking, and allowing the frozen container to come to room temperature, I drained the water out of both plastic containers. What I found was that in two days the Oil-Dri product had broken down into a slimy gray/brown mud. Very few of the original particles remained intact, and those that did were very soft and pliable.

I believe there are several different products manufactured by Oil-Dri Corporation of America, so I can't say that none of their products should be used in containers. However, based on my admittedly unscientific weekend test, there's no way I'd use Oil-Dri, at least not the stuff I bought, in any container soil mix. I've read recently on various bonsai websites that some growers use Oil-Dri or similar products and report good results, so there must be different grades or formulations of Oil-Dri.

Bottom line is that I'll stick with Turface or haydite in my containers as I *know* they won't break down in the soil mix. I'll use the remaining Oil-Dri for it's intended purpose, to clean up spills in my garage.

I made the same disappointing discovery last week, Dave. I bought a 40 lb bag of Oil-Dri at my local NAPA for $6. Even though the package differed from the photo of DE product others have found at NAPA, I hoped that it would have similar characteristics. My results were much the same as yours, though, so I'm glad that I finally found a source for Turface.

For anyone in the southeast who's looking for aged pine fines, keep an eye on your local Lowe's, especially if they carry Timberline brand pine bark mulch. I'm near Charlotte, NC, and the Lowe's in a nearby city recently added Timberline Soil Conditioner (composed exclusively of aged pine bark fines). My local Lowe's has only the mixed hardwood/pine soil conditioner I mentioned in an earlier post, so it might be hit or miss.

Thanks for the replies deep roots and shazaam. Good to know others have tried this and come up with similar results.

Thanks also for the tip on Timberline brand pine bark mulch. I'll look for it at our local Lowes once they get in their spring mulch shipments. Here in Michigan we often have different suppliers of much products than in other parts of the USA so I may not be able to find that particular product. Brands and types of mulch at the big box stores seem to vary from region to region, depending on what's locally available.

I think Turface, haydite or DE products will do well in Al's gritty soil mix. Anything else, including cat litter, oil absorber products (including brand name Oil-Dri products), etc. should be carefully tested before use. I found the results of my weekend soak test interesting, especially since the Oil-Dri bag I purchased showed a photo of the product being used for container planting.

BTW, I believe Turface and DE products are supposed to be pH neutral, but what about haydite (expanded shale, clay and slate)? Is that pH neutral as well?

Hmmm... Odd that I don't even recall making the post above, but I guess I must have. Must be CRS disease again (Can't Remember Stuff).

Anyway, I will respond to your queries and then turn the thread back over to Al.

Q:From what you have said, would it be better to use the gritty mix outdoors with water loving plants and water more frequently?

Better for what? For you the grower or the plants? I think the "best" approach is the one that allows your plants the water they require while maximizing the air to the roots. At the same time, if you choose a plant/mix/container combo that has wilted plants before you can water again then what good is all that aeration doing? Also, gardening should be a stress free, pleasurable hobby in my view. If you are sitting at work on a scorching hot day and wondering if your plants will be OK until you get home, that's stress. So, the "best" approach is the one that is enjoyable for you that also gets the plants what they need when you are away.

Al has done a tremendous job of explaining the science behind growing in containers, but we can't all be Al clones. We have to learn the material and then adapt it for our needs :)

Q: You mention making your own mixes. Have you tried any of the following combinations? If so, what did you think? And, do you find your self using the 5-1-1 style mix in small volume outdoor containers, while the gritty style mixes are more user friendly in larger outdoor containers?

I don't use many small containers. I have many whiskey barrel halves and SWC. The small containers hold succulents capable of overwintering outside such as sempervivum. Because the smaller containers hold the water shy plants I use gritty mixes. My semps, for example, are in 90% Turface and 10% bark. My Citrus which summer outside and winter indoors are in 50% bark/50% Turface. I will go to a grittier mix when I repot the citrus, it holds a bit too much water most of the year.

I tend to try to tailor the water holding capacity with my ability to water. I know from experience that if every plant I had *required* daily watering I would lose many plants. Some are able to handle this, I cannot currently.

I try not to compromise on the growing mix, instead I use larger containers than many would for the same plants or I use SWC.

That's just me though and the adaptations I have made to try to get the best results I can. In no way is what I presently do 'the best'. It is just the best I have come up with so far to meet both my and my plant's needs. Tomorrow I will likely try something differently.

In the same vein as JaG's reply, I often note that any recipes I offer are simply starting points. I might slip once in a while and refer to 'my soils' because it's so often repeated on the forums, but I really try to avoid mentioning that term. I'm not selling 'my soil' as the end all to container gardening. We know the recipes I offered work well, just from the response here; and there is enough flexibility built into the bark based soils that you can experiment with what works best for you, but it's the information other than recipes that is most valuable in these threads (credit to all participants, please).

I also frequently say that growing things is often about compromise. We can learn what might be close to the very best %s of air/water/nutrients in our soil, but dealing with the highly aerated soils may not be something everyone wants to take on. I don't mind watering every day or every other day to squeeze the extra growth or vitality from a plant, but many either cannot, or have other priorities and don't want to.

JaG's "We have to learn the material and then adapt it for our needs" is the original reason for this thread. It wasn't so readers could try to copy the recipes and expect perfect results for every application in all corners of the country. ;o) A great soil will go a long way toward making a more rewarding and productive growing experience, but knowing the why and how of what makes it work is vastly more important.

The real estate people have adopted the mantra "Location Location Location". I think if I had one, it would probably HAVE to be "Aeration Aeration Aeration". ;o) My intent when I originally posted this thread was to stress the importance of the oft forgotten property of aeration in our soils and the importance of using soils which either remain well-aerated, or adopting a strategy for insuring that aeration quickly returns to the soil before significant root damage can occur.

I'm just glad to see so many of you have learned so much (not just from me, but from all the participants) and are thinking in terms of your soil's structure, using durable ingredients, and preserving aeration. I know I'VE learned a LOT since I started this thread! ;o)

As a new member of GW I have seen this post for the first time. I am very impressed, to say the least. I have one question that i hope you can answer:

I recently purchased a number of 20 lb bags of "All-Purpose Potting Soil" manufactured for DolgenCorp by Good Earth Horticulture. Its contents list 65 - 75% Composted Pine Fines and 15 - 20% Fresh Pine Fines along with compost and sand. It appears that this formulation would make a good basic soil mixture with just a small amount of additional Peat Moss and Perlite to round it out. Does this seem reasonable or am I missing something?

It's difficult to guess exactly how it will perform w/o seeing it. I really doubt you'll need any peat in it. It sounds pretty good, but it's also possible that you would benefit from mixing a % of it with additional pine bark and/or perlite ... it depends on how much sand/compost is in the mix and how large/small the sand is and how fine the bark component is. Any chance of getting a picture posted? It includes lime in the mix?

The soil looks pretty good. You should have pretty good success in it, but there really is no way for me to judge or for you to know until you try it. My advice would be to remain mindful about over-watering. The soil should be barely damp after the plantings are established before you water again. If, after you plant in it, the soil seems to remain overly wet for extended periods, don't hesitate to use a wick to help drain the excess water. If it remains wet, it would be a signal to, next year, mix the soil with a substantial component of pine bark fines - perhaps 50/50, or 75% soil:25% fines until you get the mix right.

You could also try an experiment with a clear plastic cup. Fully saturate a measure of soil & allow it to set for an hour or so. pour it into the clear cup after you've made a good-sized hole in the bottom. You'll be able to read through the side how much perched water the soil holds. If it holds much more than a half inch or so, you should probably add some bark. I say this because further top-watering and normal breakdown will further compact the soil and increase the level of saturated soil after only a few waterings. Finally, I would make a phone call to the soil packager to see if it has had lime added. If not, add it. ;o)

The pH of both mixes will vary based on several factors (pH of the bark and peat, and other components mainly). The bark:peat:perlite mix should be somewhere around 5.0 or just below w/o liming. The gritty mix will be around 6.0 or a little lower.

How much the lime raises soil pH varies, too. A rule of thumb is: about 3 - 5 lbs of dolomitic lime will raise the pH of 1 cu yd of bark/peat soil .5 to 1 pH point. That translates to about 1/3 - 1/2 cup/cu ft or 1 tbsp per gallon.

I have not found the polymer or starch water retention beads/crystals to be helpful. Other's mileage may vary.

Al
Thanks for answering my question on cedar chips in another thread (I am glad that I checked the reply there before repeating it here).

My question here is about the small clear plastic glasses we use for rooting fig cuttings (irrespective of the rooting medium). What roll can holes in the side of the clear glass can play in aeration and avoiding or overcoming over-watered situation i.e. if more side holes will be better than fewer? I thought it provides additional sites for air access compared to the few bottom holes or from the top of the soil surface, as well as providing site for evaporation thus reducing access moisture (but then requiring relatively frequent watering). What am I missing here?

What is the pH of the mix without the lime and how much does lime raise pH as a certain ratio? Like does 1 T/5 Gal raise .3 pH or something like that?

Unfortunately there is no simple way to determine how much liming a certain amount will raise pH other than experimentation. The reason is that each full point of pH is a ten fold increase above the the previous point in hydrogen ions. For example, if a pH of 6.0 had 100 hydrogen ions (numbers are for example only, they are not accurate) then at 7.0 there would be 1,000 ions. At 8.0 there would be 10,000. So if adding a certain amount of lime raised pH by 1 point, doubling the amount wouldn't cause a 2 point rise in pH.

Looking at the math you might think that if one unit of lime raised pH by 1 unit that doubling the amount would raise pH by 1.1 units, but that generally isn't the case either :(

BTW, I e-mailed the Espoma company about their "Soil Perfector" product. According to the sales rep, their product is indeed haydite (expanded/heated shale) and is pH neutral.

Like Turface and other fired clays, haydite will hold water in it's pores and will not break down in containers, no matter how often you water.

The particle size of Soil Perfector is slightly larger than Turface. I'm not sure whether that's a big deal or not. Also Turface is generally a beige/brown color and Espoma's Soil Perfector is generally a medium gray color.

It is quite large, Dave. I have a bag of it that is more than 5 years old & I've never used it. In the o/a scheme of things, Haydite isn't very porous when compared to Turface or the calcined DE products. Also, since the PWT disappears as particle size grows to around 1/8", it's size is somewhat counterproductive to water retention. I guess what I'm trying to say is: It WILL work, but it's value is limited by its size.

I completely agree Al. I've used both Turface and haydite and have small conifers currently growing in both using your gritty mix. Both seem to work well, although gritty mix water drainage is extremely fast using haydite since the particles are larger than Turface. My pine trees that enjoy very dry soil seem to be doing especially well in the haydite/pine bark/curshed granite mix.

I only brought up haydite as an alternative for those forum members who cannot find Turface or similar product locally.

BTW, someone asked me a while back about silica sand. I bought a bag of this a couple years ago but rarely use it in my container soils. I agree with Al that you can use it but there are better things to use. About the only thing I really use it for now is for germinating seeds.

I think the sand I bought was intended for pool filters. It's quite coarse and doesn't really look like traditional sand at all.

Hi aliceinvirginia,
Your balcony railing would give you upright &/or horizontal support for tying on a wind break.
Secure it , if you can, to the out side of your balcony. This way the wind will push it against the railing stanchions & not be like a sail snapping/billowing up against the vegetation of your container crops.
Even for in ground cultivation the grower often benefits from wind breaks. Tapla's mixes are designed for the roots' world & then external environmental factors are each grower's challenge to deal with.
(Your 30+ mph wind can have sustained stronger gusts, shearing along the building side & venturi acceleration eddies in the balcony. It will be easier to allow some impact pressure release. Try to use a woven wind break, like bamboo mat/nursey cloth/sacking, rather than a solid tarp, like plastic/sheet/canvas .)

Al, just one question; is sphagnum peat the brown, fine-grained , baled stuff, or the sphagnum that is used to line hanging basket type planters? If I have both, which would be better in the 5:1:1 mix? (OK, two questions) Thanks for all your advice....Jim

They're very different. Sphagnum moss is harvested live and intact from the top of marshy bogs. It is used in many horticultural applications, but is different than the sphagnum peat that has accumulated in bogs over thousands of years. The sphagnum peat is the fine, brown product usually pressed into cubes & what we buy by the cu ft for use in soils.

Hi (: I was wondering (perhaps remarkable naively) is there a way to make pine bark BECOME pine bark fines somehow without a chipper? (I asked my dad out in Michigan if someone here in NYC who is fortunate to actually have grass could run over it with a mower to make it smaller and he laughed heartily, so I'm assuming that's out)

Are pine bark fines just extra chopped pine bark nuggets? If so, could you ask a large nursery if you could pay them to chop it for you?

Also, has anyone used Smart Pots? (Fabric pots that are supposed to have amazing aeration) It says on their instructions that you can use a heavier soil because the aeration is so much better than a normal container- just happy advertising or is this true. Should I still use Al's mix in this?

Any ideas, Al? or anyone else?

Haven't used the forum and not sure if I'm supposed to be writing someone specifically or sticking to the topic directly above me): Eek. Set me straight if I'm babbling to the wrong people or am in the wrong section.

You're fine, CC. The topic is container soils and you're certainly on topic.

Generally speaking, the pine bark fines will be partially composted, and I prefer that product for the 5:1:1 mix. I have though, seen fine pine bark that was fresh. It's easiest, of course, to find it packaged in a suitable size, but I suppose a mulching mower with a sharp blade would do the trick - if you don't mind losing a % of the bark as it flies off into space. ;o)

I've used the mesh containers pond plants are planted in for years when I want rapid growth on a plant I intend to use for bonsai. I've also used them as sort of a ICU unit for plants that are ailing. A coarse soil and lots of aeration can give almost rampant growth in this type of container.

It's not just aeration, which is primarily a function of the soil, not the container. It's partly the fact that a much greater surface area is exposed to drying air, which means you must water more frequently. This pushes unwanted gases like CO2 from the soil every time you water, and pulls a fresh supply of air in as the water percolates through the soil.

Okay-
I am yet another person that has been watching and studying and now I have to venture out and comment after much deliberation.
Al- WOW!
Thank you very much. This is the information I have been looking for. You have provided a great service and I am as impressed with your patience as I am with your knowledge and willingness to share.
I was even using my materials in the garage this weekend to run perched water table experiments in clear cups. You have awakened the geek in me.
I have recently begun collecting citrus (all container) and have agonized over the correct container mix. I have lost my fair share to what I assumed (even before reading this post) was drowning.
Apologetically, I did not venture out just to praise you. I wish to tap your brain some more. I am very interested in the gritty mix. I am not opposed to using pine bark but it will be the most difficult ingredient for me. I like the idea of a totally inorganic mix and do not like the idea of sifting mulch.
I know you support the experimentation of ther mixes and even have said you use turface alone in some circumstances. Still, please help me understand your thoughts on the 1:1:1 mix. You have said that adding higher amounts of granite to the turface will decrease water holding capability. What does adding bark do? I know it can hold water and nutrients- which turface already can do. Does bark add extra water retention over turface alone? If so, then-
Do granite and bark negate each other in water holding capabilities?
In other words, would turface alone have the some water retention as the 1:1:1 mix?
Bottom line is I am trying to decide where to start my own trials: turface alone, turface plus granite or the 1:1:1. I have a slight bias against finding and sifting bark but also like the fact bark would lighten the containers for moving inside and outside.

Bark helps lower media pH. It's less expensive than Turface, by far. It doesn't affect water-holding ability much, because the water retention of the bark component is somewhere near the average between the Turface and granite. BTW, the size of the bark is less important in the gritty mix, as long as it's not too fine, because it comprises only 1/3 of the mix. Turface alone, would have greater water retention than the 1:1:1 gritty mix.

Since I have come in your defense many times, and complimented you on almost every suggestion on your soiless mix that those of us have truly appreciated by you, here is a question since I haven't recieved an answer yet by another means.

I don't want my plants to die while I am waiting for a response to my questions.

If one is to use the 5.1.1 mix, and even the gritty soil mix, such as I do, what problems can one expect if they do not lime in the 5.1.1 mix, and what future problems can one expect to recieve if they do not add gypsum into the 1.1.1 gritty mix.
I am still having a hard time understanding the process of plants needs, or the consquences of forgetting this very important step.

If the additions of these ingrediants are skipped, due to laziness, or due to no product on hand at the time in a haste to make this soilles mix from excitement, then what can one do to correct the problems associated with the lack of any lime, or gypsum in the soils, and what problems can one expect?

I have seen a by product of failure to lime my 5.1.1 mix, now I am paying the price.
I have had severe yellowing of leaves in which you told me to add Mg after learning I forgot to lime in the 5.1.1. mix which I used for them.
Since I have become a follower of your expertise, and this good soiless mix, in which I am glad I did, I would love a follow up for when my problems occur along the way, or otherwise I might regret I ever did..

I am sure you see what I mean.
I still have not completely understood what is happening to my plants since I forgot to add lime to my 5.1.1.mix.
Sorry..:-(

I would really appreciate you're consistant help, since I am still in the process of learning from you and this wonderful soilless mix, in which I have NEVER stop appreciating. In some ways, I am still a newbie at using this mix. Al, I know is some of my plants have been doing great, up to a certain point, then what?

Hi meyermike,
The utilization of lime/gypsum/dolomite is to correct the pH of the growing medium raw materials.
The pH is important because it regulates the conditions under which ion exchanges among nutrient/fertilization minerals occur.
When the pH is improper for the uptake of certain nutrients they are not all able to be used &/or favors ion activity of certain minerals that block the ion mobility of other minerals.
The amounts of total dissolved mineral solids, in both the growing medium and/or the fertilization solution, have a limit beyond which they are not able to be taken up by the plant at a distinct pH.
Tapla has written about these dynamics, so I don't mean to steal his thunder - after all, the man plays with fire.

I have a question about Sifting the bark in 5:1:1 mix. I work at 3 jobs around 24-26 days a month so sitting there sifting pine bark is not something I have time to do. I was wondering if you good folks could tell aproxamently the size of the bark to look for at the store ie. BB size smaller than a dime so on. Also if I dont sift is it going to be the worst thing possible?
I have about a day or 2 to get the soil prepared and soaked so I need to have the most efficant and best Information possible to get everything started and planted in as little time possible.
I hope you all will be understanding about my time constraints but I love to plant and garden and I want to keep on with this pastime B/C it gives me peace from my hectic life.

Just a quick question about a couple of the components in the gritty mix that I couldn't find answered elsewhere in the forums. What are the approximate densities of the turface and the crushed granite? In other words what volume does a pound of each material take up? I live in an apartment, so I don't want purchase too much nor do I want to make additional trips.

I thought it seemed to work pretty good. I live in Dallas area where it gets very hot during the summer. I'm still learning on how much to use what ingredient... like for example taxodium (bald cypress, etc) end to suffer quickly so adding more peat seem to help. 3:1:1 is my base right now. I;ve done away with turface as it is too wasteful for my money to filter out small particles.

A cup of Turface weighs about .3 lbs or 4.8 oz, dry. A lb of dry Turface is about 3-1/3 cups. A gallon of dry Turface weighs about 4-2/3 lbs.

Judging by the bag sizes, the crushed granite (Gran-I-Grit) has about twice the bulk density of Turface. Keep in mind that Turface has 40-50% internal porosity, almost all of which holds water. Since water is much heavier than Turface, it's not out of line to estimate that Turface weighs almost twice as much wet as dry. Since there is little water-holding ability associated with the granite (except what clings to the surface or particles) it doesn't increase much in weight near as much as Turface when it is wet. From this, we can see that though dry Turface is about half the bulk density of dry granite, at absorptive capacity, their weight/volume ratio is much closer.

Thanks for the quick response. I am looking to make ~25 gallons of the mix; which from my sketchy math looks to be ~40lbs of Turface, 80lbs of crushed granite, and a little over one cubic foot (8.3 gallons) of pine bark fines. Since Turface comes in 50lb bags I will probably use the entire bag and cut down the crushed granite to ~60lbs; and add to this 1.5 cups of gypsum and 3tsp of epsom salts.

Am I in the right Turface laden ballpark with these proportions? Or is conceding crushed granite in the mix a bad idea? (I'm growing mostly citrus and a couple bamboo palms.)

Why not approach this from a volume perspective? The basic recipe is based on volume & not weight. 8-1/3 gallons each, of pine bark, Turface, and granite. If you want to adjust, keep the organic component at 1/3 or less and the inorganic component at 2/3 o/a - adjust the inorganic components as req'd. It makes life easier. ;o)
E.g.
3 parts bark
4 parts Turface
2 parts granite
yields a 2/3 inorganic:1/3 organic soil.

Don't incorporate the Epsom salts - it should be an ongoing thing, mixed with fertilizer solution (unless your fertilizer contains Mg - most don't) @ 1/4 tsp per gallon whenever you fertilize. Uncomposted, small chunks of pine bark with few (or no) fines are best in the gritty mix.

I went to the more convenient large nursery near me (Merrifield's), and bought something called Superfines. Don't know if it is a product just of that nursery.

How can I tell if it is the right stuff, or if it contains shredded hardwood as well, or if it is composted?

pH tests? I remember something about a perched water test, but I don't remember if that was for this or for the Turface.

I haven't opened the bag yet. The nursery said the sample bins have been sitting there a long time, so don't necessarily match the bag contents. The sample bin looked the size of the particles at 12 o'clock but was the color of 3 and 9.

Last year I turned up my nose at the Virginia Fines like the ones at 3 o'clock. I couldn't see what was in another bag, so I ended up buying something slightly larger from another nursery.

I should probably just have gone back to the nursery that told me that their soil conditioner was the right stuff, and where it looked like the one at the top. But it was considerably further away (Wolf Trap Nursery). I figured I'd give the names of the nurseries for other people in the DC/northern Virginia area.

How can I tell if it is the right stuff, or if it contains shredded hardwood as well, or if it is composted?

I don't know, Alice. Ask - read what it says on the bag - call the company that packages the product, smell it (piney odor), examine it to see if the bark particles are pine .....

Forget the pH tests. The PWT test was just a check to see if the soil held perched water. If you think your product is pine bark, if you follow the recipe, you should be fine, but you can do the PWT test if you're curious. Of course, my goal in providing the info here was so you could understand how 'it all goes together', but if you hang around a while, you'll eventually absorb most of it by osmosis. ;o)

Gosh, I hate to ask even more questions, but I really do want to make my own potting mix this year. I've finally found a nursery where I can buy fine pine bark mulch. It doesn't seem to be composted really, but it is what the nurseryman tells me they make their own potting mix out of...along with peat and sand. I told him about Al's mix and that it was pine bark fines, peat, perlite and lime. He said they never use lime and it isn't necessary. I'd think, since I might be buying it from him, he'd have sung its praises, but who knows?

So...why is lime necessary? Is it because the pine is acidic?

And...If the mix is 5 parts pine bark, 1 part peat and 1 part perlite - how much lime? I don't seem to see the amount anywhere, although I may have missed it.

And...is hydrated lime okay? I have a bag of that for lowering ph in the garden.

Hi, Alys. Any soil with bark and peat as the two primary components is going to be very low in Ca and Mg, and low in pH (4.5 and lower is not uncommon). Since we need to supply Ca and Mg, as well as raise pH, and dolomitic limestone does all three, it is the most preferred method of accomplishing these things. I'm not sure why your nursery person told you lime is not needed ..... well, I guess technically it isn't - you could jump through a dozen technical hoops to accomplish your goals, but it's pretty silly to do so with something as simple as dolomite at the ready. I think I would have quickly engaged him in conversation by asking him how he raises pH and how he gets Ca and Mg to the plants. I'm sure his answer would have immediately revealed whether or not you were talking to the right guy. ;o)

Your hydrated lime (calcium hydroxide) is another material which may be used for a rapid reduction of pH. However, this material contributes more ions to the soluble salt content of the media than ground limestone, and lacks Mg, setting you up for a possible Ca induced deficiency (antagonistic deficiency) of Mg. Generally speaking, the amount of hydrated lime used is reduced by 1/3-1/2 of the quantity of ground limestone used, but I wouldn't suggest using it.

As noted, the most preferred material for raising pH is dolomitic lime (a calcium/magnesium carbonate). This material reacts much the same as calcium carbonate but also supplies magnesium for plant growth. This is particularly important where magnesium is not included in the liquid or granular fertilization programs.

The actual amount of these materials to use per cubic yard of growing media is based on the CCE, cation exchange capacity and existing pH of the media, non of which any (?) of us measure. Since most of these values are not available for our soilless growing media, it is virtually impossible to precisely calculate how much material to add to achieve a desired pH. Generally speaking, growers use between 3-7 pounds of dolomitic lime/cubic yard of media to adequately buffer pH. However, the only way to be absolutely sure is through a trial and error procedure, but none (?) of us check, so we take an educated guess. I have been very happy adding 1 level tbsp dolomitic (garden) lime per gallon of the 5:1:1 mix or 1/2 cup/cu ft.

In the first post in this thread controlled release fertilizer is listed. It isn't necessary, but convenient for those who don't always keep on top of fertilizing.

The lime question is answered by the trade in general. Virtually every bag of commercially produced bark or peat based potting mix is limed by the manufacturer. Why this nursery doesn't or what they do about pH I have no idea. Al also explains why the lime is necessary.

I'm de-lurking and showing my incredible ignorance all for the love of tomatoes!

Ok, I've looked over all of the earlier threads and am humbled by how much you all know and how much I can only hope to someday learn. Since you're leaps and bounds beyond me, maybe you can chime in so that my tomatoes don't suffer from my learning curve.

So, I'm looking to have a container garden for fruiting plants (tomatoes, cucumbers, beans, peas, strawberries, etc.) I'll be growing in plastic pots. Nothing fancy or anything that requires power tools or 7 trips to the hardware store to construct. The pots will be on my brick patio. I am not open to using harmful chemical fertilizers. I'd rather forego the home garden entirely than do that (sorry).

Now my questions....what growing medium mix should I be using? I know there's the basic recipe above, but somewhere along the threads I seem to recall reading that for veggies it's best to just use 5 parts pine bark fines and 1 part peat. Is that right? I also understand (I think?) that I should be using some sort of wick to allow the drainage of "trapped" water and that since I have a brick patio, the pots can just sit directly on the patio with the wick trailing out of the pot and onto the brick (but I don't know what makes a good wick vs. a bad wick or if there's any special way to position the wick within the pot). I also have been winter sowing my seeds in a homemade potting mix of 2 pts. mushroom compost, 2 pts. peat, and 1 pt. vermiculite. How do I handle the transfer of my sprouted seeds from this medium to the preferred mix in larger containers when the time comes?

I totally don't understand fertilization or all of the wonderful nutrients and nutrient delivery agents that you have all discussed in such impressive detail. I need major guidance in this area.

Can I just have the "for Dummies" version? I just need to be told exactly what to buy (I have HD, Lowes, Meijer, Ace, etc. available to me and I'm not opposed to looking elsewhere or buying online if I know what I'm looking for). I need to know what proportions to mix, what exactly to add, how to marry pot to container to wicking system in harmony, and how to fertilize (when, with what, how much). I need it to be explained to me as if I have NO IDEA what I'm doing or how gardening works, as I'm starting to discover how much that is the case.

I promise that I will do what I am told and think of you all every time my girls stuff their faces with veggies fresh from the vine (I can hardly imagine how amazing my harvest will be this year now that I'm realizing how much I've been doing wrong in prior years).

Thank you in advance, and thank you especially to Al for your amazing body of knowledge and your equally astounding desire to impart it to others to make the world a happier, greener place.

I am not open to using harmful chemical fertilizers. I'd rather forego the home garden entirely than do that (sorry).

To put it nicely calling inorganic, water soluble nutrients, the only nutrients plants can use 'harmful chemicals' is silly. It reflects a basic misunderstanding.

Using organic matter results in soil life processing the organic matter which results in inorganic, water soluble nutrients. Using water soluble, inorganic nutrients from the get go bypasses the soil life which is desirable in a container where that soil life doesn't thrive.

There is nothing harmful about it.

I will leave your other questions to others or to your rereading the thread, I just chimed in due to my frustration with organic minded growers (of whom I am one) calling synthetic fertilizers "harmful chemicals" when they are simply essential plant nutrients in a form plants can use right now without waiting for 'soil life' to work on them.

What works well in the soil works well because of the soil. There is no soil in containers and if there were one would have major drainage/aeration issues.

You need to change your mindset. Containers aren't the earth nor are they filled with them. Different rules apply.

As you might easily guess, I would steer you toward a minor variation of the mix you described & have you add 1 part perlite to the mix.

Wicks you use for drainage needn't be as absorbent as those you use to pull water up into the container for irrigation purposes, but I've found that strips from 100% rayon mop heads, or strips cut from 100% rayon (man made chamois) are great. The wick should be secure in the soil and contact the soil at the lowest part of the container. It doesn't matter if it is in the middle & more is not better.

I'm surprised that you have had good results with the shroom compost, peat, vermiculite mix (have you?) because of it's likely high salt content & extreme water retention. Handle the transfer to this mix as you would to any other. Try to keep roots as intact as possible & keep the media moist and humidity high until the seedlings have established.

Fertilizer: I'm not being harsh or on a high horse - just frank when I say I'm not going to tell you what to buy unless you relent on the all-organic approach. It's not that I'm trying to beat-up on you for being organic minded - not at all; it's just that I have no idea how to advise you to proceed with an organic agenda that will deliver the effort:reward quotient that soluble fertilizers will offer in containers. I've tried the organic approach, and though I adhere tightly to it in the gardens/beds, I find it very troublesome, & frankly, much less productive in containers. I'll have to leave you to your research on this subject. If you want guidance as to what soluble fertilizers are appropriate, please ask and I (or someone else) will be happy to help. ;o)

Thank you too, for your kind words and the thank-you. I really appreciate it. ;o)

To be clear, I was using the term "harmful" as a qualifier. I can only assume (forgive my ignorance) that there may be some fertilizers that are not 100% pure organic matter that have been deemed to be essentially harmless (aka not harmful) due to the way that they are or are not processed by the plant vs. other applications that may in fact be harmful or potentially more harmful than others particularly when the plant, or portions of the plant, will ultimately be consumed by young children.

I am not educated enough to speak to what these more, less, or non-harmful non-organic fertilizers might be, and I was hoping that some of you are. I was merely trying to distinguish my priorities and clarify that am willing to compromise some degree of productivity and appearance in my fruit to avoid harmful chemicals (harmful ones, not necessarily ALL of them-unless they're all harmful but you seem to suggest that it not the case, so I assume that you can advise me on which ones to use) being applied to what will be an edible plant.

With regard to the planting medium. It looks like the recommendation is 5 pt. pine bark fines that are smallish (as pictured in the examples-likely to be found at HD, Lowes, or Meijer-labeled "pine bark fines" or mulch?) 1 pt. peat (already have) and 1 pt. perlite (I'll order online). Sound right?

Oh, and I forgot to say that I'm not married to any particular mix for WSing the seeds. If you have a better suggestion, I'm all ears (and have many seeds yet to sow). I just used the mix recommended on the WSing board.

Sounds like you have the mix right, HG. Don't forget the lime, though.

If I was starting seeds, I would go to the NAPA car parts store & buy a $7.50 bag of Floor-Dry. I would mix it with sphagnum peat at 5 parts Floor-Dry: 1 part peat and use no fertilizer until the first set of true leaves starts to emerge - then a 1/4 recommended strength dose each week until planting time.

Ideally, a fertilizer with a 2:1:2 or a 1:1:2 ratio that has all the nutrients (or include a micronutrient (MN)supplement) would be best. Alternately, any 1:1:1 fertilizer (with MNs or a MN supplement) supplemented with a little 0-0-3 ProTeKt (a potassium supplement that also contains silicon) would really help to strengthen the seedlings.

I am not educated enough to speak to what these more, less, or non-harmful non-organic fertilizers might be, and I was hoping that some of you are. I was merely trying to distinguish my priorities and clarify that am willing to compromise some degree of productivity and appearance in my fruit to avoid harmful chemicals (harmful ones, not necessarily ALL of them-unless they're all harmful but you seem to suggest that it not the case, so I assume that you can advise me on which ones to use) being applied to what will be an edible plant.

None of the synthetic fertilizers are harmful to humans unless one eats it directly. They are just nutrients. Think vitamins. Miracle Grow, Foliage Pro, Dynamite, Schultz etc. are all fine to use.

Plants use inorganic, water soluble nutrients. Those nutrients can be contained in organic matter and released over time by soil critters (largely absent in a container) or they can be prepackaged in water soluble, inorganic form so the plants can use them right away.

There is nothing at all harmful about using them on plants kids will eat. My own kids eat them. Virtually every produce item you buy at the store or eat at a restaurant was grown using synthetic fertilizers.

I can understand being concerned about pesticides, but not plant nutrients.

Root crops (potatoes, onions, radishes, yams, etc.), with all the container gardening talk, I would like to try growing some more vegetables in containers this year. While the container mixes that Al suggests seem great for most plants, does anyone have any ideas for modifying the mix for root crops or experience proving the mix is useful in these applications as well?

Onions aren't root crops ;) They are actually better thought of as a leafy crop, like lettuce is.

Anyway, why would a mix suitable for growing veggies and flowery stuff *not* work for potatos, onions and radish?

I don't really grow potatos, but I have grown onions and radish in mixes similar to Al's 5-1-1 mix and it works just fine. There really isn't anything special about the mix other than it provides better than average aeration to the roots while holding on to a reasonable amount of water.

That is a recipe for success with any plant regardless which part of the plant we want to eat.

Provided I water and fertilize properly, I would like to experiment with the gritty mix. With vegetables like potatoes and yams, I was concerned the weight of the mix would not expand as well as a fluffy peat-based mix.

Also, I appreciate your feedback on radishes and onions doing well in a modified 5-1-1 mix. I would like my container vegetables to have at least the same vigor as when grown in my raised beds. In looking at onions growing from another thread, I am wondering if the larger tote-style containers would do better with exceptional drainage and aeration.

It seems that field grown vegetables get larger and display more health in general.

With vegetables like potatoes and yams, I was concerned the weight of the mix would not expand as well as a fluffy peat-based mix.

Well, think of it this way. Would it's weight be greater or lesser than the typical garden/field soil folks grow them in?

I am curious though as to why you would choose the gritty mix over the 5-1-1 mix for veggies.

I am not going to suggest it won't work well (never tried it), but it seems... unusual to build a long lasting mix for a short term plant. Is the idea to reuse it pretty much forever? It seems that field grown vegetables get larger and display more health in general

I used to frequently hear/read folks saying it was unreasonable to expect container grown plants to do as well as ground grown plants. I never understood that. If we are 100% meeting the plant's requirements for optimal growth, what difference would growing in a container make versus in ground?

In a container we have more control over nutrients, moisture levels and with an appropriate potting mix, aeration.

About the only limiting factors I can think of are potting mix volume and lack of temperature insulation.

justaguy2,
Yes, I was considering the gritty mix for a long-term use with short-term plants. At end of season, I was considering a hydrogen peroxide or bleach solution, followed by an adequate rinse. This would be for 22" diameter pots that would be left out over winter and re-used in spring. I was considering periodic fertilizing with slow-release Osmocote and occasional watering with Maxi-Crop sea kelp solution. Watering would be done with drip irrigation.

You mention container volume and temperature buffering, both of which are good points. I try for larger containers, but am looking at ways to control temperature spikes in late summer.

If I can fine tune the process, I may end up doing more vegetable gardening in containers.

It was in Indianapolis, but I don't remember the place I bought it now. That was more than 10 years ago.

Peastone doesn't work well because of its wide variance in size. When I talk to groups about soils/container gardening, I use a clear plastic canister filled with a quart of boulder-size marbles. I point out the wonderful aeration the space between the marbles offers. I say "This canister is completely full of marbles ..... can't get any more in it - right?" Then I add a pint of BBs to the quart. So now I have 1-1/2 quarts in a 1 quart container. Finally, I add another pint of fine sand, so I've put 2 quarts in a 1 quart container, destroying that wonderful aeration in the process. That is peastone.

I suppose if you wanted to screen out everything that passes through insect screen and what's left on top of 1/8 or 3/16 hardware cloth (depending on the application) you could use it; but if you're going to do THAT ..... crushed granite is prescreened, and for what volume of peastone you'll have left after screening - less expensive and no work. Not a difficult decision, for me. ;o)

Mary, See if any of the garden centers around you carry Schultz Soil conditioner in 5lb bags. It's Turface inside, at a premium per pound price. Don't be confused by other products called 'Soil Conditioner' that are bark/wood products, Turface looks more like clay kitty litter and will be the Schultz brand. I believe there are some other sources of it in 5lb bags, but can't recall names.

Thanks Justaguy2,
I checked Schultz - they no longer package the soil conditioner. I am looking into the kitty litter route or the aquatic soil route. I have looked at local nurseries and hardware stores with no success. Maybe it is too early in the "growing season" here.

Well I'm committed to using Al's mix this year, and it looks like I'm going to have a LOT of it! The only thing I'm having trouble finding is the lime for some reason. Hydrated lime is everywhere, dolomite, not so much. Found the bark for $40 a "scoop" - they don't sell lesser quantities. Peat and perlite I can find at Lowe's. For the gritty mix I found both granite grit and turface for $8 for a 50 lb bag. Again, can't buy less. I'm not sure how big a 50 lb bag is, but judging by the 40 lb bags of dogfood I buy - it's a LOT.

I have two large (4' x 18") planters that I think I'll use the gritty mix in even though I plant petunias and cucumbers in them, since I hate the thought of emptying them every year because of the size. Other than that, I don't actually have many perennials. I was wondering, what would it do if I used the turface in place of the perlite in the regular mix? If it doesn't hurt anything, would I need to change anything else?

If you use Turface in place of Perlite (something I do often) you have a heavier container and the Turface will hold more water than perlite.

In my 5 gallon bucket test, Turface will hold a larger volume of water than small sized, uncomposted bark fines will.

AZ,

If you use kitty litter or Oil-Dry or other Turface replacements be sure to soak a sample in a cup of water overnight and check it in the morning. Some folks get lucky and find it stays solid, others, like me, find it turn to clay muck. It seems that those who find a suitable replacement have it remain suitable from bag to bag and those who don't find them suitable also have a consistent experience from bag to bag. Seems to be a regional manufacturing thing.

Also, thanks for the info on Schultz, I didn't realize they stopped offering it.

Using Turface in place of perlite would extend the interval between necessary waterings a bit, yes. It's one of the reasons I use it in place of perlite myself (it's also why I use large containers for anything that pouts quickly if the moisture levels are on the dry side of moist).

If you use a fast draining mix that maintains no PWT (or maintains an inconsequential PWT given root depth/container height) you are freed to water as often as you like (because air spaces are being maintained), but by choosing the amount of water each ingredient can hold on to you can extend the interval at which watering becomes a necessity.

Frequent waterings are still helpful to bring in fresh oxygen and push potentially harmful gasses out before they become a problem.

Sounds good. I have a week in the height of summer I'm always out of town and I hate the idea of having to get a friend or neighbor to water several times so if I can water less often that'll do. I think I'll still buy the perlite and use it in containers where weight is a question, but if I have a ton of turface left over after doing the perennials, I'll likely incorporate that into my bigger pots. Thanks!

Husband picked up the turface and granite today since those stores close before I get off work. In thinking I'd have really big bags, I wasn't thinking about the fact that granite is a ROCK! Duh. So...not as much as I thought. Is there any substitute for the granite so I don't have to buy a bunch more?

It really boils down to being mainly about size. I use the granite because the size is so close to perfect. It's purpose in the soil is to add to the bulk of the soil, contribute to macro-porosity (big air pores), and help reduce water retention. Other substitutes would be lava rock (pumice) in the same size, Haydite in the same size, or perlite. Perlite is very light and plants that don't tolerate fluoride well might not like a soil with a 1/3 perlite component.

I wanted to try sifting some of my bark through a few different size screens and record the results. I have alot of bark ready to be used that I sifted through 1/4 inch screen. There is alot of fine stuff in there. I want to sift some through a insect screen to get the real fine bark out and use the top stuff. Also some through a 1/8 screen and use the stuff that stays on top. Then some of the bark that went through the 1/8 screen, resift that through an insect screen and use that stuff.Then finaly use the bark that passed through the 1/4 screen without doing more to except add more perlite then the others. And see how the same plants do, filix

I have been going through my bookmarks lately, cleaning house so to speak. In the process I have come upon a few old gems.

One that I wanted to share with everyone with an interest in this thread is this one.

It's an article from Ohio State university on physical characteristics of growing media. The reason I am putting it in this thread is because as I reread through it I had to chuckle at how similar the author sounded to Al. I had to check to see who the author was to make sure it wasn't Al :)

In many ways this article says the same thing Al does, but in a little different way, but they both still sound quite alike. See what you think.

"Al I'm sure you already know what the outcome will be. Am I waisting my time?"

I have a pretty good idea, but your actually seeing the results will give you a better feel/understanding, and additional confidence when you make future soil decisions. No matter how it turns out, it won't be wasted effort - experience is a good teacher. It's the same kind of thing I used to do while the whole 'soil thing' was coming together in my mind.

Thanks Al. I'm thinking the bark that goes through a 1/4 inch but won't go through an 1/8 inch might be the best. Because it will be very fast. Just more work to keep wet.
justa, cool link. Does sound alot like Al. Good science is good science. filix

Mmhmm - that will make a very fast soil if you're using it at 5:1:1 or close. I don't screen the partially composted fines that I use in the 5:1:1 mix & use 1/4" pre-screened fir bark in the gritty mix.

Hi Al! I think of your advice to us often and I always try to follow the principles of good container media that you have so generously shared with us. For all of this I thank you. Now I have a specific question regarding the levels of dolomitic lime you suggest to use in your pine bark fines based mixture. Your post at this website from March 19, 2005 specified to use "1 cup lime" in your big batch recipe. Now at the beginning of this post, you recommend that "2 cups lime." On checking pH of mixes made with 1 cup lime/big batch, I found it to be around 6.0 to 6.5 pH which would be a good pH range for most lime-requiring plants. What accounts for your change of lime levels?
Thanks so much Al.
Nathan

4-6 lbs of dolomite will generally raise the pH of 1 yard of media by 0.5 - 1.0 point. 16 (fl) oz of dolomite weighs about 1 lb, so we can use ounces interchangeably (fluid vs weight) for lime. Bark/peat soils usually come in at an unlimed pH of 4.0 - 5.0, so we want to raise them about >1.0 point.

There are 80 oz in 5 lbs of lime, or 160 tbsp, which will raise the pH of a yard (202 gallons) of soil about 1 point. The big batch is about 35 gallons (4.5 cu ft) or 1/6 of a yard. We need 1/6 of 160 tbsp or 27 tbsp to raise the pH about 1 point. There are 16 tbsp in a cup, so 27 tbsp is 1.7 cups. Since we need to raise the pH more than 1 point, we round the 1.7 cups up 0.3 cups to 2.0 cups.

The change comes as a result of realizing that supplying a single cup of lime might not have raised pH high enough. This can ensure that Ca remains reactive and relatively unavailable instead of (in the case of adding more dolomite) residual and exchangeable.

Pine bark fines are just pine bark that has been chipped or ground to a fine size. It may or may not be composted or partially composted. Partially composted pine bark fines have composted in piles, usually from one harvest season to the next.

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